Allen, D. (2001). Getting Things Done. Penguin Books.
Dyfyniad Arddull ChicagoAllen, David. Getting Things Done. New Delhi: Penguin Books, 2001.
Dyfyniad MLAAllen, David. Getting Things Done. Penguin Books, 2001.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.