Robbins, N. B. (2005). Creating more effective graphs. John Wiley.
Dyfyniad Arddull ChicagoRobbins, Naomi B. Creating More Effective Graphs. London: John Wiley, 2005.
Dyfyniad MLARobbins, Naomi B. Creating More Effective Graphs. John Wiley, 2005.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.