Analog Science Fiction - Science Fact April 1991 (Vol.111, No.5)
Cover by Nicholas Jainschigg (for "The Great Unknown.")

Serial: "The Great Unknown" (Part 1 of 3) by Harry Turtledove (part of Earthgrip)

Novelettes: "I'll Show You Mine If..." by F. Alexander Brejcha ("Centaurs" series)
"The Future Is Now" by David L. Burkhead
"A Most Singular Murder" by John Dalmas.

Science Fact: "Starships, Robots, and Space Travel for the Next Millenium" by Geoffrey A. Landis.

Stories "Conquest" by F. M. Busby
"Of the Last Kind" by P. J. Plauger.

Stanley Schmidt's editorial is "Ex Machina."