BARRA RALPH. (1983). PUTTING QUALITY CIRCLES TO WORK: A PRACTICAL STRATEGY FOR BOOSTING PRODUCTIVITY & PROFITS. MCGRAW-HILL.
Lua i Stíl Chicago (17ú heag.)BARRA RALPH. PUTTING QUALITY CIRCLES TO WORK: A PRACTICAL STRATEGY FOR BOOSTING PRODUCTIVITY & PROFITS. LONDON: MCGRAW-HILL, 1983.
Lua MLA (9ú heag.)BARRA RALPH. PUTTING QUALITY CIRCLES TO WORK: A PRACTICAL STRATEGY FOR BOOSTING PRODUCTIVITY & PROFITS. MCGRAW-HILL, 1983.
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