APA
Denis Walker, . (1990). Customer first : a strategy for quality service. Gower Publ, England: .
Chicago
Denis Walker, . 1990. Customer first : a strategy for quality service. Gower Publ, England: .
Harvard
Denis Walker, . (1990). Customer first : a strategy for quality service. Gower Publ, England: .
MLA
Denis Walker, . Customer first : a strategy for quality service. Gower Publ, England: . 1990.