Context Aware Computing-Global Market Status & Trend Report 2013-2023 Top 20 Countries Data
![](/report_cover/10724/context-aware-computing-global-market-status-trend-report-2013-2023-top-20-countries-data_en.gif)
Report Summary
Context Aware Computing-Global Market Status & Trend Report 2013-2023 Top 20 Countries Data offers a comprehensive analysis on Context Aware Computing industry, standing on the readers? perspective, delivering detailed market data in Global major 20 countries and penetrating insights. No matter the client is industry insider, potential entrant or investor, the report will provides useful data and information. Key questions answered by this report include:
Worldwide and Top 20 Countries Market Size of Context Aware Computing 2013-2017, and development forecast 2018-2023
Main manufacturers/suppliers of Context Aware Computing worldwide and market share by regions, with company and product introduction, position in the Context Aware Computing market
Market status and development trend of Context Aware Computing by types and applications
Cost and profit status of Context Aware Computing, and marketing status
Market growth drivers and challenges
The report segments the global Context Aware Computing market as:
Global Context Aware Computing Market: Regional Segment Analysis (Regional Production Volume, Consumption Volume, Revenue and Growth Rate 2013-2023):
North America (United States, Canada and Mexico)
Europe (Germany, UK, France, Italy, Russia, Spain and Benelux)
Asia Pacific (China, Japan, India, Southeast Asia and Australia)
Latin America (Brazil, Argentina and Colombia)
Middle East and Africa
Global Context Aware Computing Market: Type Segment Analysis (Consumption Volume, Average Price, Revenue, Market Share and Trend 2013-2023):
Hardware
Software
Global Context Aware Computing Market: Application Segment Analysis (Consumption Volume and Market Share 2013-2023; Downstream Customers and Market Analysis)
Academia and education
Banking financial services and insurance
Consumer goods and retail
Health Care
Others
Global Context Aware Computing Market: Manufacturers Segment Analysis (Company and Product introduction, Context Aware Computing Sales Volume, Revenue, Price and Gross Margin):
Apple
Amazon
Facebook
Google
Microsoft
IBM
In a word, the report provides detailed statistics and analysis on the state of the industry; and is a valuable source of guidance and direction for companies and individuals interested in the market.
Context Aware Computing-Global Market Status & Trend Report 2013-2023 Top 20 Countries Data offers a comprehensive analysis on Context Aware Computing industry, standing on the readers? perspective, delivering detailed market data in Global major 20 countries and penetrating insights. No matter the client is industry insider, potential entrant or investor, the report will provides useful data and information. Key questions answered by this report include:
Worldwide and Top 20 Countries Market Size of Context Aware Computing 2013-2017, and development forecast 2018-2023
Main manufacturers/suppliers of Context Aware Computing worldwide and market share by regions, with company and product introduction, position in the Context Aware Computing market
Market status and development trend of Context Aware Computing by types and applications
Cost and profit status of Context Aware Computing, and marketing status
Market growth drivers and challenges
The report segments the global Context Aware Computing market as:
Global Context Aware Computing Market: Regional Segment Analysis (Regional Production Volume, Consumption Volume, Revenue and Growth Rate 2013-2023):
North America (United States, Canada and Mexico)
Europe (Germany, UK, France, Italy, Russia, Spain and Benelux)
Asia Pacific (China, Japan, India, Southeast Asia and Australia)
Latin America (Brazil, Argentina and Colombia)
Middle East and Africa
Global Context Aware Computing Market: Type Segment Analysis (Consumption Volume, Average Price, Revenue, Market Share and Trend 2013-2023):
Hardware
Software
Global Context Aware Computing Market: Application Segment Analysis (Consumption Volume and Market Share 2013-2023; Downstream Customers and Market Analysis)
Academia and education
Banking financial services and insurance
Consumer goods and retail
Health Care
Others
Global Context Aware Computing Market: Manufacturers Segment Analysis (Company and Product introduction, Context Aware Computing Sales Volume, Revenue, Price and Gross Margin):
Apple
Amazon
Microsoft
IBM
In a word, the report provides detailed statistics and analysis on the state of the industry; and is a valuable source of guidance and direction for companies and individuals interested in the market.
CHAPTER 1 OVERVIEW OF CONTEXT AWARE COMPUTING
1.1 Definition of Context Aware Computing in This Report
1.2 Commercial Types of Context Aware Computing
1.2.1 Hardware
1.2.2 Software
1.3 Downstream Application of Context Aware Computing
1.3.1 Academia and education
1.3.2 Banking financial services and insurance
1.3.3 Consumer goods and retail
1.3.4 Health Care
1.3.5 Others
1.4 Development History of Context Aware Computing
1.5 Market Status and Trend of Context Aware Computing 2013-2023
1.5.1 Global Context Aware Computing Market Status and Trend 2013-2023
1.5.2 Regional Context Aware Computing Market Status and Trend 2013-2023
CHAPTER 2 GLOBAL MARKET STATUS AND FORECAST BY REGIONS
2.1 Market Development of Context Aware Computing 2013-2017
2.2 Sales Market of Context Aware Computing by Regions
2.2.1 Sales Volume of Context Aware Computing by Regions
2.2.2 Sales Value of Context Aware Computing by Regions
2.3 Production Market of Context Aware Computing by Regions
2.4 Global Market Forecast of Context Aware Computing 2018-2023
2.4.1 Global Market Forecast of Context Aware Computing 2018-2023
2.4.2 Market Forecast of Context Aware Computing by Regions 2018-2023
CHAPTER 3 GLOBAL MARKET STATUS AND FORECAST BY TYPES
3.1 Sales Volume of Context Aware Computing by Types
3.2 Sales Value of Context Aware Computing by Types
3.3 Market Forecast of Context Aware Computing by Types
CHAPTER 4 GLOBAL MARKET STATUS AND FORECAST BY DOWNSTREAM INDUSTRY
4.1 Global Sales Volume of Context Aware Computing by Downstream Industry
4.2 Global Market Forecast of Context Aware Computing by Downstream Industry
CHAPTER 5 NORTH AMERICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
5.1 North America Context Aware Computing Market Status by Countries
5.1.1 North America Context Aware Computing Sales by Countries (2013-2017)
5.1.2 North America Context Aware Computing Revenue by Countries (2013-2017)
5.1.3 United States Context Aware Computing Market Status (2013-2017)
5.1.4 Canada Context Aware Computing Market Status (2013-2017)
5.1.5 Mexico Context Aware Computing Market Status (2013-2017)
5.2 North America Context Aware Computing Market Status by Manufacturers
5.3 North America Context Aware Computing Market Status by Type (2013-2017)
5.3.1 North America Context Aware Computing Sales by Type (2013-2017)
5.3.2 North America Context Aware Computing Revenue by Type (2013-2017)
5.4 North America Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 6 EUROPE MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
6.1 Europe Context Aware Computing Market Status by Countries
6.1.1 Europe Context Aware Computing Sales by Countries (2013-2017)
6.1.2 Europe Context Aware Computing Revenue by Countries (2013-2017)
6.1.3 Germany Context Aware Computing Market Status (2013-2017)
6.1.4 UK Context Aware Computing Market Status (2013-2017)
6.1.5 France Context Aware Computing Market Status (2013-2017)
6.1.6 Italy Context Aware Computing Market Status (2013-2017)
6.1.7 Russia Context Aware Computing Market Status (2013-2017)
6.1.8 Spain Context Aware Computing Market Status (2013-2017)
6.1.9 Benelux Context Aware Computing Market Status (2013-2017)
6.2 Europe Context Aware Computing Market Status by Manufacturers
6.3 Europe Context Aware Computing Market Status by Type (2013-2017)
6.3.1 Europe Context Aware Computing Sales by Type (2013-2017)
6.3.2 Europe Context Aware Computing Revenue by Type (2013-2017)
6.4 Europe Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 7 ASIA PACIFIC MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
7.1 Asia Pacific Context Aware Computing Market Status by Countries
7.1.1 Asia Pacific Context Aware Computing Sales by Countries (2013-2017)
7.1.2 Asia Pacific Context Aware Computing Revenue by Countries (2013-2017)
7.1.3 China Context Aware Computing Market Status (2013-2017)
7.1.4 Japan Context Aware Computing Market Status (2013-2017)
7.1.5 India Context Aware Computing Market Status (2013-2017)
7.1.6 Southeast Asia Context Aware Computing Market Status (2013-2017)
7.1.7 Australia Context Aware Computing Market Status (2013-2017)
7.2 Asia Pacific Context Aware Computing Market Status by Manufacturers
7.3 Asia Pacific Context Aware Computing Market Status by Type (2013-2017)
7.3.1 Asia Pacific Context Aware Computing Sales by Type (2013-2017)
7.3.2 Asia Pacific Context Aware Computing Revenue by Type (2013-2017)
7.4 Asia Pacific Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 8 LATIN AMERICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
8.1 Latin America Context Aware Computing Market Status by Countries
8.1.1 Latin America Context Aware Computing Sales by Countries (2013-2017)
8.1.2 Latin America Context Aware Computing Revenue by Countries (2013-2017)
8.1.3 Brazil Context Aware Computing Market Status (2013-2017)
8.1.4 Argentina Context Aware Computing Market Status (2013-2017)
8.1.5 Colombia Context Aware Computing Market Status (2013-2017)
8.2 Latin America Context Aware Computing Market Status by Manufacturers
8.3 Latin America Context Aware Computing Market Status by Type (2013-2017)
8.3.1 Latin America Context Aware Computing Sales by Type (2013-2017)
8.3.2 Latin America Context Aware Computing Revenue by Type (2013-2017)
8.4 Latin America Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 9 MIDDLE EAST AND AFRICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
9.1 Middle East and Africa Context Aware Computing Market Status by Countries
9.1.1 Middle East and Africa Context Aware Computing Sales by Countries (2013-2017)
9.1.2 Middle East and Africa Context Aware Computing Revenue by Countries (2013-2017)
9.1.3 Middle East Context Aware Computing Market Status (2013-2017)
9.1.4 Africa Context Aware Computing Market Status (2013-2017)
9.2 Middle East and Africa Context Aware Computing Market Status by Manufacturers
9.3 Middle East and Africa Context Aware Computing Market Status by Type (2013-2017)
9.3.1 Middle East and Africa Context Aware Computing Sales by Type (2013-2017)
9.3.2 Middle East and Africa Context Aware Computing Revenue by Type (2013-2017)
9.4 Middle East and Africa Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 10 MARKET DRIVING FACTOR ANALYSIS OF CONTEXT AWARE COMPUTING
10.1 Global Economy Situation and Trend Overview
10.2 Context Aware Computing Downstream Industry Situation and Trend Overview
CHAPTER 11 CONTEXT AWARE COMPUTING MARKET COMPETITION STATUS BY MAJOR MANUFACTURERS
11.1 Production Volume of Context Aware Computing by Major Manufacturers
11.2 Production Value of Context Aware Computing by Major Manufacturers
11.3 Basic Information of Context Aware Computing by Major Manufacturers
11.3.1 Headquarters Location and Established Time of Context Aware Computing Major Manufacturer
11.3.2 Employees and Revenue Level of Context Aware Computing Major Manufacturer
11.4 Market Competition News and Trend
11.4.1 Merger, Consolidation or Acquisition News
11.4.2 Investment or Disinvestment News
11.4.3 New Product Development and Launch
CHAPTER 12 CONTEXT AWARE COMPUTING MAJOR MANUFACTURERS INTRODUCTION AND MARKET DATA
12.1 Apple
12.1.1 Company profile
12.1.2 Representative Context Aware Computing Product
12.1.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Apple
12.2 Amazon
12.2.1 Company profile
12.2.2 Representative Context Aware Computing Product
12.2.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Amazon
12.3 Facebook
12.3.1 Company profile
12.3.2 Representative Context Aware Computing Product
12.3.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Facebook
12.4 Google
12.4.1 Company profile
12.4.2 Representative Context Aware Computing Product
12.4.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Google
12.5 Microsoft
12.5.1 Company profile
12.5.2 Representative Context Aware Computing Product
12.5.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Microsoft
12.6 IBM
12.6.1 Company profile
12.6.2 Representative Context Aware Computing Product
12.6.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of IBM
CHAPTER 13 UPSTREAM AND DOWNSTREAM MARKET ANALYSIS OF CONTEXT AWARE COMPUTING
13.1 Industry Chain of Context Aware Computing
13.2 Upstream Market and Representative Companies Analysis
13.3 Downstream Market and Representative Companies Analysis
CHAPTER 14 COST AND GROSS MARGIN ANALYSIS OF CONTEXT AWARE COMPUTING
14.1 Cost Structure Analysis of Context Aware Computing
14.2 Raw Materials Cost Analysis of Context Aware Computing
14.3 Labor Cost Analysis of Context Aware Computing
14.4 Manufacturing Expenses Analysis of Context Aware Computing
CHAPTER 15 REPORT CONCLUSION
CHAPTER 16 RESEARCH METHODOLOGY AND REFERENCE
16.1 Methodology/Research Approach
16.1.1 Research Programs/Design
16.1.2 Market Size Estimation
16.1.3 Market Breakdown and Data Triangulation
16.2 Data Source
16.2.1 Secondary Sources
16.2.2 Primary Sources
16.3 Reference
1.1 Definition of Context Aware Computing in This Report
1.2 Commercial Types of Context Aware Computing
1.2.1 Hardware
1.2.2 Software
1.3 Downstream Application of Context Aware Computing
1.3.1 Academia and education
1.3.2 Banking financial services and insurance
1.3.3 Consumer goods and retail
1.3.4 Health Care
1.3.5 Others
1.4 Development History of Context Aware Computing
1.5 Market Status and Trend of Context Aware Computing 2013-2023
1.5.1 Global Context Aware Computing Market Status and Trend 2013-2023
1.5.2 Regional Context Aware Computing Market Status and Trend 2013-2023
CHAPTER 2 GLOBAL MARKET STATUS AND FORECAST BY REGIONS
2.1 Market Development of Context Aware Computing 2013-2017
2.2 Sales Market of Context Aware Computing by Regions
2.2.1 Sales Volume of Context Aware Computing by Regions
2.2.2 Sales Value of Context Aware Computing by Regions
2.3 Production Market of Context Aware Computing by Regions
2.4 Global Market Forecast of Context Aware Computing 2018-2023
2.4.1 Global Market Forecast of Context Aware Computing 2018-2023
2.4.2 Market Forecast of Context Aware Computing by Regions 2018-2023
CHAPTER 3 GLOBAL MARKET STATUS AND FORECAST BY TYPES
3.1 Sales Volume of Context Aware Computing by Types
3.2 Sales Value of Context Aware Computing by Types
3.3 Market Forecast of Context Aware Computing by Types
CHAPTER 4 GLOBAL MARKET STATUS AND FORECAST BY DOWNSTREAM INDUSTRY
4.1 Global Sales Volume of Context Aware Computing by Downstream Industry
4.2 Global Market Forecast of Context Aware Computing by Downstream Industry
CHAPTER 5 NORTH AMERICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
5.1 North America Context Aware Computing Market Status by Countries
5.1.1 North America Context Aware Computing Sales by Countries (2013-2017)
5.1.2 North America Context Aware Computing Revenue by Countries (2013-2017)
5.1.3 United States Context Aware Computing Market Status (2013-2017)
5.1.4 Canada Context Aware Computing Market Status (2013-2017)
5.1.5 Mexico Context Aware Computing Market Status (2013-2017)
5.2 North America Context Aware Computing Market Status by Manufacturers
5.3 North America Context Aware Computing Market Status by Type (2013-2017)
5.3.1 North America Context Aware Computing Sales by Type (2013-2017)
5.3.2 North America Context Aware Computing Revenue by Type (2013-2017)
5.4 North America Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 6 EUROPE MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
6.1 Europe Context Aware Computing Market Status by Countries
6.1.1 Europe Context Aware Computing Sales by Countries (2013-2017)
6.1.2 Europe Context Aware Computing Revenue by Countries (2013-2017)
6.1.3 Germany Context Aware Computing Market Status (2013-2017)
6.1.4 UK Context Aware Computing Market Status (2013-2017)
6.1.5 France Context Aware Computing Market Status (2013-2017)
6.1.6 Italy Context Aware Computing Market Status (2013-2017)
6.1.7 Russia Context Aware Computing Market Status (2013-2017)
6.1.8 Spain Context Aware Computing Market Status (2013-2017)
6.1.9 Benelux Context Aware Computing Market Status (2013-2017)
6.2 Europe Context Aware Computing Market Status by Manufacturers
6.3 Europe Context Aware Computing Market Status by Type (2013-2017)
6.3.1 Europe Context Aware Computing Sales by Type (2013-2017)
6.3.2 Europe Context Aware Computing Revenue by Type (2013-2017)
6.4 Europe Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 7 ASIA PACIFIC MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
7.1 Asia Pacific Context Aware Computing Market Status by Countries
7.1.1 Asia Pacific Context Aware Computing Sales by Countries (2013-2017)
7.1.2 Asia Pacific Context Aware Computing Revenue by Countries (2013-2017)
7.1.3 China Context Aware Computing Market Status (2013-2017)
7.1.4 Japan Context Aware Computing Market Status (2013-2017)
7.1.5 India Context Aware Computing Market Status (2013-2017)
7.1.6 Southeast Asia Context Aware Computing Market Status (2013-2017)
7.1.7 Australia Context Aware Computing Market Status (2013-2017)
7.2 Asia Pacific Context Aware Computing Market Status by Manufacturers
7.3 Asia Pacific Context Aware Computing Market Status by Type (2013-2017)
7.3.1 Asia Pacific Context Aware Computing Sales by Type (2013-2017)
7.3.2 Asia Pacific Context Aware Computing Revenue by Type (2013-2017)
7.4 Asia Pacific Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 8 LATIN AMERICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
8.1 Latin America Context Aware Computing Market Status by Countries
8.1.1 Latin America Context Aware Computing Sales by Countries (2013-2017)
8.1.2 Latin America Context Aware Computing Revenue by Countries (2013-2017)
8.1.3 Brazil Context Aware Computing Market Status (2013-2017)
8.1.4 Argentina Context Aware Computing Market Status (2013-2017)
8.1.5 Colombia Context Aware Computing Market Status (2013-2017)
8.2 Latin America Context Aware Computing Market Status by Manufacturers
8.3 Latin America Context Aware Computing Market Status by Type (2013-2017)
8.3.1 Latin America Context Aware Computing Sales by Type (2013-2017)
8.3.2 Latin America Context Aware Computing Revenue by Type (2013-2017)
8.4 Latin America Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 9 MIDDLE EAST AND AFRICA MARKET STATUS BY COUNTRIES, TYPE, MANUFACTURERS AND DOWNSTREAM INDUSTRY
9.1 Middle East and Africa Context Aware Computing Market Status by Countries
9.1.1 Middle East and Africa Context Aware Computing Sales by Countries (2013-2017)
9.1.2 Middle East and Africa Context Aware Computing Revenue by Countries (2013-2017)
9.1.3 Middle East Context Aware Computing Market Status (2013-2017)
9.1.4 Africa Context Aware Computing Market Status (2013-2017)
9.2 Middle East and Africa Context Aware Computing Market Status by Manufacturers
9.3 Middle East and Africa Context Aware Computing Market Status by Type (2013-2017)
9.3.1 Middle East and Africa Context Aware Computing Sales by Type (2013-2017)
9.3.2 Middle East and Africa Context Aware Computing Revenue by Type (2013-2017)
9.4 Middle East and Africa Context Aware Computing Market Status by Downstream Industry (2013-2017)
CHAPTER 10 MARKET DRIVING FACTOR ANALYSIS OF CONTEXT AWARE COMPUTING
10.1 Global Economy Situation and Trend Overview
10.2 Context Aware Computing Downstream Industry Situation and Trend Overview
CHAPTER 11 CONTEXT AWARE COMPUTING MARKET COMPETITION STATUS BY MAJOR MANUFACTURERS
11.1 Production Volume of Context Aware Computing by Major Manufacturers
11.2 Production Value of Context Aware Computing by Major Manufacturers
11.3 Basic Information of Context Aware Computing by Major Manufacturers
11.3.1 Headquarters Location and Established Time of Context Aware Computing Major Manufacturer
11.3.2 Employees and Revenue Level of Context Aware Computing Major Manufacturer
11.4 Market Competition News and Trend
11.4.1 Merger, Consolidation or Acquisition News
11.4.2 Investment or Disinvestment News
11.4.3 New Product Development and Launch
CHAPTER 12 CONTEXT AWARE COMPUTING MAJOR MANUFACTURERS INTRODUCTION AND MARKET DATA
12.1 Apple
12.1.1 Company profile
12.1.2 Representative Context Aware Computing Product
12.1.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Apple
12.2 Amazon
12.2.1 Company profile
12.2.2 Representative Context Aware Computing Product
12.2.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Amazon
12.3 Facebook
12.3.1 Company profile
12.3.2 Representative Context Aware Computing Product
12.3.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Facebook
12.4 Google
12.4.1 Company profile
12.4.2 Representative Context Aware Computing Product
12.4.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Google
12.5 Microsoft
12.5.1 Company profile
12.5.2 Representative Context Aware Computing Product
12.5.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of Microsoft
12.6 IBM
12.6.1 Company profile
12.6.2 Representative Context Aware Computing Product
12.6.3 Context Aware Computing Sales, Revenue, Price and Gross Margin of IBM
CHAPTER 13 UPSTREAM AND DOWNSTREAM MARKET ANALYSIS OF CONTEXT AWARE COMPUTING
13.1 Industry Chain of Context Aware Computing
13.2 Upstream Market and Representative Companies Analysis
13.3 Downstream Market and Representative Companies Analysis
CHAPTER 14 COST AND GROSS MARGIN ANALYSIS OF CONTEXT AWARE COMPUTING
14.1 Cost Structure Analysis of Context Aware Computing
14.2 Raw Materials Cost Analysis of Context Aware Computing
14.3 Labor Cost Analysis of Context Aware Computing
14.4 Manufacturing Expenses Analysis of Context Aware Computing
CHAPTER 15 REPORT CONCLUSION
CHAPTER 16 RESEARCH METHODOLOGY AND REFERENCE
16.1 Methodology/Research Approach
16.1.1 Research Programs/Design
16.1.2 Market Size Estimation
16.1.3 Market Breakdown and Data Triangulation
16.2 Data Source
16.2.1 Secondary Sources
16.2.2 Primary Sources
16.3 Reference