The Magazine of Fantasy and Science Fiction: July 1967 (Volume 33, Number1)
Cover by Jack Gaughan (for "The Day Before Forever.")

Short Novel: "The Day Before Forever" by Keith Laumer.

Stories: "Balgrummo's Hell" by Russell Kirk
"Alter Ego" by Hugo Correa
"Encounter in the Past" by Robert Nathan
"The Master's Thesis" by David Madden
"The Sea Monster and the Mayor of New York City" by Gahan Wilson
"The Vitanuls" by John Brunner.
"Flight Between Realities" (verse) by Doris Pitkin Buck.

Science: "Twelve Point Three Six Nine" by Isaac Asimov.