APA
Gray G. R., Darley H. & Darley H. (1980). Composition and properties of oil well drilling fluids. Houston: Gulf Publishing.
Chicago
Gray George R, Darley H.C.H and Darley H.C.H. 1980. Composition and properties of oil well drilling fluids. Houston: Gulf Publishing.
Harvard
Gray G. R., Darley H. and Darley H. (1980). Composition and properties of oil well drilling fluids. Houston: Gulf Publishing.
MLA
Gray George R, Darley H.C.H and Darley H.C.H. Composition and properties of oil well drilling fluids. Houston: Gulf Publishing. 1980.