Berry, C. (2011). The sustainable procurement guide: Procuring sustainably using BS 8903. BSi.
Dyfyniad Arddull ChicagoBerry, Cathy. The Sustainable Procurement Guide: Procuring Sustainably Using BS 8903. London: BSi, 2011.
Dyfyniad MLABerry, Cathy. The Sustainable Procurement Guide: Procuring Sustainably Using BS 8903. BSi, 2011.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.