Weigend, M., M.  Gottschling, F.  Selvi, and H. H.  Hilger. 2009. ?Marbleseeds are gromwells - Systematics and evolution of Lithospermum and allies (Boraginaceae tribe Lithospermeae) based on molecular and morphological data?. Molecular Phylogenetics and Evolution 52(3):755 - 768. Retrieved  (http://www.sciencedirect.com/science/article/B6WNH-4WBK7BK-3/2/5ef424fa3684d5c985634011154460d5).

Gottschling, M., F.  Luebert, H. H.  Hilger, and J. S.  Miller. 2014. ?Molecular delimitations in the Ehretiaceae (Boraginales)?. Molecular Phylogenetics and Evolution 72:1 - 6. Retrieved  (http://www.sciencedirect.com/science/article/pii/S1055790313004405).