This checklist is taken from: Helping the retarded _ a systematic approach / E.A. Perkins, P.D. Taylor, A.C.M. Capie, 2nd ed.
Previous ed.: 1976.
Developmental checklist by E. A. Perkins. ISBN 0906054257. Published by British Institute of Mental Handicap in 1980. Publication and catalogue information, links to buy online and reader comments.