The Cargille-Allen gem testing set :
comprising the refractoscope and Cargille specific gravity liquids.

APA Citation

Allen, R. Morris., R.P. Cargille Laboratories. (1957). The Cargille-Allen gem testing set: comprising the refractoscope and Cargille specific gravity liquids. New York, N.Y.: R. P. Cargille Laboratories.

MLA Citation

Allen, Roy Morris, 1882-, and R.P. Cargille Laboratories. The Cargille-Allen Gem Testing Set: Comprising the Refractoscope And Cargille Specific Gravity Liquids. New York, N.Y.: R. P. Cargille Laboratories, 1957.

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