Uncaged: Faces of Sigil (Planescape Accessory), by R. V. Vallese
The Planewalkers Handbook (AD&D/ Planescape), by Monte Cook
Monstrous Compendium Appendix II (Planescape) (Advanced Dungeons & Dragons, 2nd Edition, Accessory/2613), by Rich Baker
Tales from the Infinite Staircase (AD&D/Planescape Adventure), by Cook, Monte
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