The second IF reader of science fiction

In the Arena, 1963, Brian W. Aldiss The Billiard Ball, 1967, Isaac Asimov The Time-Tombs, 1963, J. G. Ballard "Die, Shadow!", 1963, Algis Budrys The Foundling Stars, 1966, Hal Clement Toys for Debbie, 1965, David A. Kyle Forest in the Sky, [Retief], 1967, Keith Laumer At the Core, [Known Space], 1966, Larry Niven Under Two Moons, 1965, Frederik Pohl Masque of the Red Shift, [Berserker], 1965, Fred Saberhagen