Revelle Humanities Grammar Handbook
6 Sentence fragments
7 Run-on sentences
8 Verb agreement
13 Passive voice
15 ESL
17 Misplaced modifiers
18 Pronoun reference
20a Comparisons
21 Parallel construction
23 Commas
23d Sexist language
25/6 Semicolons & colons
29 Ellipsis
31 Brackets
35 Apostrophes
36 Abbreviations
37 Underlining
39 Numbers
41b Slang
41e Jargon
41f Pretentious language
42c Idioms
42e Clichés
43a Fluff

37 Underlining
You should underline titles of books and foreign words or phrases. When you refer to the titles of long works (novels, plays, books of history or philosophy, long poems), underline them; when you refer to the titles of short works (essays, short stories, and — naturally — short poems), put them in quotation marks.

Exceptions are the Koran, the Bible, and individual books of the Bible (such as Exodus or the New Testament).

Incorrect: Aristophanes' "The Clouds" uses the device known as deus ex machina.

Revised: Aristophanes' The Clouds uses the device known as deus ex machina.

Note: Italics are the equivalent of underlining, so they may be used interchangeably.