For Petrosedum
Messerschmid, T.F.E., J.T. Klein, G. Kadereit, and J.W. Kadereit. 2020. Linnaeus's folly -- phylogeny, evolution and classification of Sedum (Crassulaceae) and Crassulaceae subfamily Sempervivoideae. Taxon 69: 892-926. Google Scholar
Nikulin, V.Y., S.B. Gontcharova, R. Stephenson, and A.A. Gontcharov. 2016. Phylogenetic relationships between Sedum L. and related genera (Crassulaceae) based on ITS rDNA sequence comparisons. Flora 224: 218-229. Google Scholar
Thiede, J., and U. Eggli. 2007. Crassulaceae. In Kubitzki, K., C. Bayer, and P.F. Stevens, eds. 2007. The families and genera of vascular plants. IX. Flowering plants – Eudicots – Berberidopsidales, Buxales, Crossosomatales, Fabales p.p., Geraniales, Gunnerales, Myrtales p.p., Proteales, Saxifragales, Vitales, Zygophyllales, Clusiaceae alliance, Passifloraceae alliance, Dilleniaceae, Huaceae, Picramniaceae, Sabiaceae. Springer, Berlin. 509 pp. Google Scholar