Undated (15th century?), Tibet, Mahasiddha Virupa, copper alloy, private collection, published on Himalayan Art Resources.
Mahasiddha Virupa, 15th c?, Tibet, c.a., skull cup+long-life vase, incised meditation belt, private on HAR
Himalayan Buddhist Art – Art Bouddhiste de l'Himalaya
5th to 18th century Buddhist Art of the Himalayas (sculpture)
Himalayan Buddhist Art - Art Bouddhiste de l'Himalaya 
