Nine Princes in Amber
Roger Zelazny · 1970 · Novel
This series established a major fantasy framework for the multiverse, introducing the concept of a 'true' reality from which infinite 'shadow' realities are cast, and demonstrating how a protagonist can traverse and manipulate these worlds.
What it is
Corwin, an amnesiac prince, discovers he is from Amber, the one true reality, and that all other worlds, including Earth, are merely 'Shadows' of Amber. He must navigate these infinite parallel worlds to reclaim his throne.
↓Passed on to(2)
While very different in tone and genre, the concept of distinct, accessible parallel worlds with varying societal structures, as explored in Amber, could subtly inform Russ's construction of alternate female-dominant societies.
The central premise of a character from a 'prime' reality learning to 'verse-jump' and draw skills from infinite parallel selves, and the idea of a central nexus (Amber/Alpha-verse), shows conceptual lineage.