His Elements of the Kabbalah remains a fundamental text for the student of ceremonial magick.
In general usage, the spelling qabalah is used to distinguish the variation of kabbalah used by western or hermetic magicians from Jewish mystical kabbalah.
See also: Tree of Life Note: Crowley used the spelling "Qabalah" (an approximate transliteration) and that spelling is retained in Thelemic literature.
The spelling "Kabbalah" is used in reference to traditional Hebrew mysticism, and "Cabala" in reference to the Christian overlays of the same.
The word "Kabbalah" is derived from the Hebrew root "to receive, to accept", and in many cases is used synonymously with "tradition".
Probably the most influential Kabbalistic document, the "Sepher ha Zohar", was published by Moses de Leon, a Spanish Jew, in the latter half of the thirteenth century.