Semple, J. C., J. G. Chmielewski & M. E. Lane. 1989. Chromosome number determinations in fam. Compositae, tribe Astereae. III. Additional counts and comments on generic limits and ancestral base numbers. Rhodora 91: 296–314.
Semple, J. C., J. G. Chmielewski & C. Xiang. 1992. Chromosome number determinations in fam. Compositae, tribe Astereae. IV. Additional reports and comments on the cytogeography and status of some species of Aster and Solidago. Rhodora 94: 48–62.
Semple, J. C., J. Zhang & C. Xiang. 1993. Chromosome number determinations in fam. Compositae, tribe Astereae. V. Eastern North American taxa. Rhodora 95: 234–253.