• The Library of Congress considers working papers and technical papers as part of the "valuable gray literature in business, economics and law".
• Harvard Business School defines a working paper as summarizing "original research in a narrow segment of a field of study, and is intended by publication within a period of one to three yeras".
• Working papers are issued by such institutions as think tanks, universities, various Federal Reserve banks international agencies and foreign central banks. 
  
• One of the best known publishers of working papers is the National Bureau of Economic Research.

National Bureau of Economic Research (NBER)

Harvard Business School Working Papers Collection

Office of Tax Policy Research at the University of MIchigan

Library of Congress, Business Reference Services: Working Papers and Technical Reports in Business, Economcis and Law

Centre for Economic Forecasting (London Business School)

Center for Manufacturing and Operations Management (University of Rochester, William E. Simon Graduate School Of Business Administration, Rochester, New York)

Center for Mathematical Studies in Economics and Management Science (Northwestern University, Evanston, Illinois)

Center for the Study of American Business (Washington University, St. Louis)

Columbia International Affairs Online

C.V. Starr Center for Applied Economics (New York University)

Erasmus, Research Institute of Management Report Series

Faculty of Business Administration (National University of Singapore)

Finance and Economics Discussion Series

Graduate School of Business (Stanford University)

Industrial Relations Section (Princeton University, New Jersey)

Institute of Finance and Accounting (London Business School)

John M. Olin School of Business (Washington University, St. Louis)

Management Information Systems Research Center (University of Minnesota)

Marketing Science Institute