Does Vajrayana Buddhism incorporate the use of cannabis? I'm reading a Wikipedia article on Vajrayana Buddhism and it says: "In Tantric Buddhism, which originated in the Tibeto-Himalayan region, cannabis serves as an important part of a traditional ritual..."

It cites a journal that I don't have access to, so I can't look too much deeper into the source.

What's the historical background of this claim? Are there serious documents or Buddhist texts showing the use of cannabis or other drugs?
There's a copy of the referenced article here: The Religious and Medicinal
Uses of Cannabis
in China, India and Tibet by MIA TOUW.

The relevant quote from the article (which was copied into Wikipedia) is,


  In
  Tantric Buddhism, which flowered in the TibetoHimalayan region, cannabis is an important part of the
  meditative ritual which may or may not include sexual
  intercourse. It is taken to facilitate the meditation and
  heighten awareness of all aspects of the ceremony. The
  large dose, taken orally, is timed so as to ensure
  increasingly heightened awareness from the beginning of
  the ritual onwards, with the greatest "high"-delayed when
  taken orally by about an hour and a half- coinciding with
  the climax of the ceremony (Bharati 1965). Secular use, both medicinal and
  recreational, is equally widespread but, as Sharma (1977b)
  notes, cannabis is taken for granted in the Himalayas and
  therefore is not much discussed.


The "Bharati 1965" reference is


  Bharati, A. 1965. The Tantric Tradition. London: Rider &amp; Co.


There's a Wikipedia article about the author of that reference -- Agehananda Bharati.

The book is available for bout $20 from Amazon -- The Tantric Tradition Mass Market Paperback – January 1, 1970