English Grammar for the Utterly Confused - Laurie Rozakis 2003

Periods
Chapter 10 Punctuation
Part 4 A Writers Tools

1. Use a period after a complete sentence.

The shrimp’s heart is in its head.

In the Arctic, the sun sometimes appears to be square.

2. Use a period after most abbreviations and initials. If an abbreviation comes at the end of a sentence, do not add another period.

Dr.

Ms.

Jr.

John F. Kennedy

3. Don’t use a period after acronyms.

CNN

ABC

CBS

4. Use a period after each Roman numeral, letter, or number in an outline.