The Blue Book provides a list of the representatives of Member States to the United Nations. The complete collection from 1946 up to today is now conveniently accessible and searchable in the UN Digital Library.

Direct link to the Blue Book in the UN Digital Library: https://digitallibrary.un.org/search?ln=en&as=1&m1=p&p1=Permanent+Missions+to+the+United+Nations&f1=series&op1=a&m2=a&p2=&f2=&op2=a&m3=a&p3=&f3=&dt=&d1d=&d1m=&d1y=&d2d=&d2m=&d2y=&rm=&ln=en&sf=year&so=d&rg&_gl=1*k1yp5i*_ga*MTgxODEwODUwNS4xNzE1ODAwOTE1*_ga_TK9BQL5X7Z*MTcxODk4MzQ3NS4yLjEuMTcxODk4MzUwOC4wLjAuMA..

This database includes officers of the Department who were Presidential appointees (appointed by the President with the advice and consent of the Senate) and chiefs of bureaus who hold rank equivalent to Assistant Secretary of State. These include: Secretaries, Deputy Secretaries, Under Secretaries, Deputy Under Secretaries, Assistant Secretaries, Counselors, Legal Advisers, Chiefs of Protocol, and certain administrators.

Other positions have, from time to time, been included in the database based on their particular circumstances. The complete lists of heads of the United States Information Agency (USIA), for example, are included. USIA was incorporated into the Department in 1999. Other Chiefs of Mission of particular historical interest have also been included.