Pfeiffer, J. W. (1989). The Encyclopedia of group activities: 150 practical designs for successful facilitating. University Associates.
Dyfyniad Arddull ChicagoPfeiffer, J. William. The Encyclopedia of Group Activities: 150 Practical Designs for Successful Facilitating. San Diego, Calif.: University Associates, 1989.
Dyfyniad MLAPfeiffer, J. William. The Encyclopedia of Group Activities: 150 Practical Designs for Successful Facilitating. University Associates, 1989.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.