- p.70 Terry B.Grandstaff, The Hmong, Opium, and the Haw, speculations on the origin of their association, The Siam Society, Bangkok
- Letter from Bill Geddes to Michael Moerman, April 24, 1959
- P.71 Terry B.Grandstaff, The Hmong, Opium, and the Haw, speculations on the origin of their association, The Siam Society, Bangkok