In THE SELECTED LETTERS 1974, PKD mentions kabala/cabala/qabalah/etc. three times (not sure which as I only have my Index handy - I used 'Cabala') : (1). In a letter to Claudia Bush, 7-22-1974, SL 74 page 200ff (also in the EXEGESIS, page 37). (2). In a letter to Louise Zimmerman, 7-25-1974, SL 74 page 214ff. (3). In a letter to the Roiscrucian Supply Bureau, 9-30-1974, SL 74 page 256. Indexes are fun!