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AMA Manual of Style Committee

Contents

Abbreviations

Chapter:
Plurals
Author(s):

Brenda Gregoline

For most all-capital abbreviations, the plural is formed by adding s. Do not use an apostrophe before the s. (See also 8.7.5, Punctuation, Apostrophe, Using Apostrophes to Form Plurals.)

CIs

HMOs

EEGs

ICUs

ORs

RBCs

Note: When plural all-capital-letter abbreviations are found in an all-capital setting, such as a first-level heading, the plural s is still lowercase.

REFERRAL PATTERNS IN MIDWESTERN HMOs