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APICS dictionary
Cox, James F., (1998)
IGCSE business studies
Borrington, Karen, (1999)
Springers Handbuch der Betriebswirtschaftslehre
Berndt, Ralph,
Business in context : an introduction to business and its environment
Needle, David, (1994)
Needle, David, (2010)
Needle, David, (2004)