The lecture notes of Ludwig Wittgenstein's 1933–1934 Cambridge class, on the philosophy of language

Blue book is used in various fields and often refers to an almanac or other compilation of statistics and information. Specifically:

The nickname given to a parliamentary paper. In the 19th century, many of these were issued with a blue cover, and the term was applied to all parliamentary papers. Now obsolete.

Project Blue Book, a U.S. Air Force study on UFOs

A weekly digest of signals intelligence reports by the British intelligence agency GCHQ

A common name of the book Smalltalk-80: The Language and its Implementation, and any virtual machine implementation based on it

The publications of the European Central Bank describing the main payment and securities settlement systems in the EU Member States

The Java Virtual Machine Specification

A set of telecommunications Recommendations issued by the International Telecommunication Union Standardisation Sector in 1988

A guide to houses of prostitution in the Storyville district of New Orleans, published between 1895 and 1915

Kelley Blue Book, an automotive appraisal firm

Treachery of the Blue Books, an 1847 Welsh parliamentary report on the state of education in the country

The World Jewellery Confederation Blue Book is a three-part publication outlining terminology, classification and ethical guidelines (i.e. disclosure of treatments and synthetics) for coloured gemstones, diamonds and pearls.

Blue Book protocol, the File Transfer Protocol of the Coloured Book protocols

Bluebook, a citation guide used in law review articles or legal documents

Blue Books, spacecraft data and telemetry recommendations made by the Consultative Committee for Space Data Systems

Blue Book (magazine), published from 1905 to 1975

The nickname of the annual publication of the Motor Sports Association

Blue Book specification, the name of one format from the Rainbow Book standards for compact discs, defining the Enhanced CD standard

Blue book exam, a type of test involving writing an essay

A common name of the Handbook of United States Coins by R.S. Yeoman

Wisconsin Blue Book, an almanac of state government affairs and statistics. Several other states produce similar publications. For example, [1]

Aircraft Bluebook, a digest that covers the price and condition of used general aviation aircraft in the U.S; the Aircraft Bluebook Rating Scale (or "Bluebook scale") is used in the aviation industry to rate the condition of used aircraft

Blue Book (United States Marine Corps), a bulletin listing the lineal precedence and seniority of Marine Corps officers

Blue Book (racing), a publication of The Jockey Club

Annual reports produced by the governments of each crown colony and protectorate of the British Empire

Project UFO, a 1978 television series about fictional UFO investigators, created by Jack Webb, and based loosely on the United States Air Force investigation known as "Project Blue Book".