Gaya APA

HALE, G, A. (1996). THE LEADER'S EDGE: Mastering the 5 Skills of Breakthrough Thinking / Guy Hale . USA: McGraw-Hill Book Company.

Gaya MLA

HALE, Guy, A.. "THE LEADER'S EDGE: Mastering the 5 Skills of Breakthrough Thinking / Guy Hale". USA: McGraw-Hill Book Company, 1996. Text.