An introduction to mental retardation: a programmed text /
[by] Walter H. Ehlers, Curtis H. Krishef [and] Jon C. Prothero.

APA Citation

Ehlers, W. H., Prothero, J. C., Krishef, C. H. (1973). An introduction to mental retardation: a programmed text. Columbus, Ohio: C.E. Merrill Pub. Co..

MLA Citation

Ehlers, Walter H, Jon C Prothero, and Curtis H Krishef. An Introduction to Mental Retardation: a Programmed Text. Columbus, Ohio: C.E. Merrill Pub. Co., 1973.

Warning: These citations may not always be complete (especially for serials).