Astounding Science Fiction February 1955 (Volume 54, Number 6)
Illustrations by Kelly Freas, H. R. van Dongen, Wagoner. Cover by Kelly Freas (for "Time Crime.")

Serial: "Time Crime" (Part 1 of 2) by H. Beam Piper (a "Paratime" story.)

Novelette: "Citadel" by Algis Budrys.

Stories: "Design Flaw" by Lee Correy (Hank Stine)
"Tight Squeeze" by Dean C. Ing (his first story - he didn't become really active until the Seventies)
"Grandpa" by James H. Schmitz.

Science: "Hemoglobin and the Universe" by Isaac Asimov.

John W. Campbell's editorial is "Second-Order Logic?"; Book reviews by P. Schuyler Miller.