Am not sure these are exactly what you want, but:
International Stereoscopic Union; c/o Judy Fentress; PO Box 19-119; Hamilton,
New Zealand. The USA Rep is Paul Milligan; 508 Cima Circle; Gallup, NM,
87301, USA; Phone 505-722-5831
National Stereoscopic Union; PO Box 14801; Columbus, OH, 43214. MRA