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Dyfyniad Arddull ChicagoSigma Insight Group. Corporate Strategy. Seoul, korea: Sigma Insight Group, 2004.
Dyfyniad MLASigma Insight Group. Corporate Strategy. Sigma Insight Group, 2004.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.