Eric Bluestine's blogpost

Rudolf Flesch - The Art of Clear Thinking

The Unfolding of Language - Book

Gordon archives at the University of South Carolina Search for Sugarloaf

Darrel Walters - Eric Bluestine's recommendation for the best writing on MLT. I'll update this with a link later on.
And more on writing well. Darrel is the absolute best in helping professionals become excellent writers.

Sandra Trehub's research - Search for her and other scholarly authors here.