Malcolm Farmer submitted a cite for the form "three-di" from a reprint of James Tiptree's "Collision"; Mike Christie verified it in the 1986 first magazine appearance. Mike Christie submitted a 1948 cite from John D. MacDonald's "School for the Stars", but it is used here just as an abbreviation for "three-dimensional" (albeit in an science-fictional context) rather than to refer to a three-D television system or something similar.

We would like cites of any date from other sources.