+ of London. Series B. Biological Sciences}, \bold{263}, 589--591.
+
+ Sargent, R. D. (2004) Floral symmetry affects speciation rates in
+ angiosperms. \emph{Proceedings of the Royal Society of London. Series
+ B. Biological Sciences}, \bold{271}, 603--608.
+
+ Vamosi, S. M. (2007) Endless tests: guidelines for analysing non-nested
+ sister-group comparisons. An addendum. \emph{Evolutionary Ecology
+ Research}, \bold{9}, 717.