parallel universes
What Mad Universe by Fredric Brown
What Mad Universe – A pulp fiction magazine editor is transported into another universe where an intergalactic war is going on, major cities are under complete blackouts, and he is being hunted for being an Arcturian spy.
Journey to Barkut by Murray Leinster
A hock-shop relic leads Tony Gregg on a Journey to Barkut, a riotous land of djinns and sins, dragons and dreams, walking castles and talking sand.
The City of Singing Flame by Clark Ashton Smith
The City of Singing Flame by Clark Ashton Smith – two stories of adventure into parallel universes. Despite its weird beauty, and its function as a portal to the Inner Dimension, the Singing Flame of Ydmos must be destroyed.
The Solar Invasion by Manly Wade Wellman
The Solar Invasion by Manly Wade Wellman
Captain Future, Joan Randall and the Futuremen cruise to a strange world in a different dimension, peopled with weird pallid inhabitants on the quest to find the Moon which was mysteriously plucked from the sky! This full length Captain Future novel by Manly Wade Wellman (1903-1986) is from 1946.