65. Possessive of proper nouns, abbreviations, and numbers

Possessive of proper nouns, abbreviations, and numbers
Chapter Contents / Possessives / The General Rule
The general rule stated at 7.16 extends to the possessives of proper nouns, including names ending in s, x, or z, in both their singular and plural forms, as well as abbreviations and numbers.
Singular forms
• Kansas’s legislature
• Chicago’s lakefront
• Marx’s theories
• Jesus’s adherents
• Berlioz’s works
• Tacitus’s Histories
• Borges’s library
• Dickens’s novels
• Malraux’s masterpiece
• Josquin des Prez’s motets
Plural forms
• the Lincolns’ marriage
• the Williamses’ new house
• the Martinezes’ daughter
• dinner at the Browns’ (that is, at the Browns’ place)
Abbreviations and numbers
• FDR’s legacy
• HP Inc.’s latest offerings
• Apollo 11’s fiftieth anniversary
Avoid forming the possessive of an abbreviation that is followed by a spelled-out form in parentheses (or vice versa).
• the long history of IBM (International Business Machines)
• not
• IBM’s (International Business Machines’) long history


From: www.chicagomanualofstyle.org/book/ed17/part2/ch07/psec017.html