=80. Possessive Case
Use an apostrophe and an s to indicate the
possessive case singular, no matter whether the word ends in one or two
s's: as, Burns's house, Furness's hat. Use the apostrophe and
s to indicate the possessive case plural when the plural does not end
in s: as, men's meeting, children's shoes. Use only the apostrophe
to indicate the possessive case plural when the plural ends in s: as,
boys' hats, ladies' outfitter. In names of corporations, cases of
joint authorship, etc., where two names are equally in the possessive
case, put the apostrophe, or the apostrophe and s, only after the name
nearest the thing possessed: as, Farmers and Merchants' bank, Allen
and Bowen's "Classical Mythology."
 Occasional exceptions to this general rule are found,
where euphony would be violated by the additional s:
as, Ulysses' son, Moses' staff.
=81. Possessive Pronouns
Do not use the apostrophe before the s in
possessive pronouns: as, its, hers, theirs.
Use an apostrophe in contracted words to indicate
the omission of letters: as, couldn't, he'll, you're.
Next: The Hyphen