9.5 Abbreviations.

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