S. J.  WAGSTAFF, OLMSTEAD, R. G., and CANTINO, P. D., ?Parsimony Analysis of cpDNA Restriction Site Variation in Subfamily Nepetoideae (Labiatae)?, Am J Bot, vol. 82, pp. 886?892, 1995.

S. J.  WAGSTAFF and OLMSTEAD, R. G., ?Phylogeny of Labiatae and Verbenaceae Inferred from rbcL Sequences?, Systematic Botany, vol. 22, pp. 165?179, 1997.

P. D.  CANTINO, OLMSTEAD, R. G., and WAGSTAFF, S. J., ?A comparison of phylogenetic nomenclature with the current system: a botanical case study?, Systematic Biology, vol. 46, p. 313, 1997.

S. J.  WAGSTAFF, Hickerson, L., Spangler, R., Reeves, P. A., and OLMSTEAD, R. G., ?Phylogeny in Labiatae sl, inferred from cpDNA sequences?, Plant Systematics and Evolution, vol. 209, pp. 265?274, 1998.