A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Agencies, companies, and other organizations
Abbreviations
Part III. Style 20 spelling

You may use abbreviations in text and elsewhere for the names of government agencies, broadcasting companies, associations, fraternal and service organizations, unions, and other groups that are commonly known by acronyms or initialisms (see 24.1.1). Spell out the full name on first reference, followed by the abbreviation in parentheses (see 24.1.2). Such abbreviations are in full capitals with no periods. Here is a representative list of such abbreviations; other names within these categories (for example, ABA, CBS, and NEH) should be treated similarly.

AAAS

AFL-CIO

AMA

AT&T

CDC

CNN

EU

FTC

HMO

NAACP

NAFTA

NFL

NIMH

NSF

OPEC

TVA

UN

UNESCO

VA

WHO

YMCA

If a company is not commonly known by an abbreviation, spell out and capitalize its name in the text. You may omit the terms Inc. or Ltd. from the name, and do not capitalize the word the at the beginning of the name.

Merck and Company

the University of Chicago Press

In tables, figures, and citations, you may also use the following abbreviations in company names. Note the differences in capitalization and punctuation.

Assoc.

Bros.

Co.

Corp.

Inc.

LP (limited partnership)

Ltd.

Mfg.

PLC (public limited company)

RR (railroad)

Ry. (railway)