University of Ottawa (Canada)
University of Ottawa: The Comma
The University of Ottawa's Writing Center developed this site. The major sections of the site are "Comma Usage" and "Superfluous Commas." Right and wrong examples are included, along with links for definitions.
McGraw Hill
Mayfield Handbook: Restrictive and Nonrestrictive
This section of the Mayfield Handbook on restrictive and nonrestrictive modifiers and clauses features a definition with links to other parts of the sentence (modifiers, clauses, phrases) along with examples of restrictive and...