January 1992 Vol. 73 #1 - AC: TOS Special Effects Article
Here's the Link to the Original October 1967 American Cinematographer Article:
Of particular relevance to TOS - The issue stands out as the earliest professional behind-the-scenes coverage of a Star Trek production, pre-dating the book The Making of Star Trek by a year.
UPDATE: October 2016
Pleased to report that in Celebration of Trek's 50th anniversary
American Cinematographer Magazine Reprinted the Original 1967 Article On-line!
It can be found here: @ http://www.theasc.com/site/blog/web-exclusives/star-trek-50-original-series-effects/