Nancy's Wordsmithy: Rules You Don't Have to Obey, Part III
http://www.stcboston.org/archives/articles/wordsmith1.shtml

Allison, Nancy
Boston Broadside
1989

Abstract:

The funny thing is, this rule should be running out of steam, because certain standards of written English have changed in ways that make the rule at least partly obsolete. Learning it is kind of like learning to change a cloth ribbon on an old manual typewriter.