Bob Olsen
3 appearances across 3 restored issues — every one readable in full, free.
Amazing Stories, Vol. 2 No. 11 — 1928 “Four Dimensional Surgery” Read the full issue (103 pages) → 
Amazing Stories, Vol. 3, No. 2 — 1928 “Four Dimensional Robberies” · p.102 Read the full issue (100 pages) → 
Amazing Stories, January 1931 — 1931 “The Man Who Annexed the Moon” Read the full issue (100 pages) → Appearances are extracted from each issue's own printed contents page; entries we can't read confidently are withheld rather than guessed.