This is Giant Superman 23, published by Mimosa (SA Magazine Co) +/- 1963-1964.
It reprints the cover and both stories from DC Comics' Adventure Comics 286 (1961):
"The Witch of Smallville"
"Bizarro, Private Detective"
Also reprinted is this story from DC Comics' Action Comics 248 (1969):
Congo Bill: "The Amazing Congorilla"
Also reprinted is this story from DC Comics' Action Comics 297 (1962):
Supergirl: "The Forbidden Weapons of Krypton"
48pages, glossy colour cover, black and white newsprint interior.
Here is the cover of issue 23 and DC Comics' original cover: