WILLBORN WALTER O. (1994). GLOBAL MANAGEMENT OF QUALITY ASSURANCE SYSTEMS. MCGRAW-HILL.
Lua i Stíl Chicago (17ú heag.)WILLBORN WALTER O. GLOBAL MANAGEMENT OF QUALITY ASSURANCE SYSTEMS. NEW YORK: MCGRAW-HILL, 1994.
Lua MLA (9ú heag.)WILLBORN WALTER O. GLOBAL MANAGEMENT OF QUALITY ASSURANCE SYSTEMS. MCGRAW-HILL, 1994.
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