Allen, D. (2015). Getting Things Done The art of Stress Free Productivity. Piatkus.
Dyfyniad Arddull ChicagoAllen, David. Getting Things Done The Art of Stress Free Productivity. London: Piatkus, 2015.
Dyfyniad MLAAllen, David. Getting Things Done The Art of Stress Free Productivity. Piatkus, 2015.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.