Gottschling, M., and H. H.  Hilger. 2001. ?Phylogenetic analysis and character evolution of Ehretia and Bourreria (Ehretiaceae, Boraginales) and their allies based on {ITS1} sequences?. 123:249?268.

Gottschling, M., J. S.  Miller, M.  Weigend, and H. H.  Hilger. 2005. ?Congruence of a phylogeny of Cordiaceae (Boraginales) inferred from {ITS1} sequence data with morphology, ecology, and biogeography?. 92:425?437.

Gottschling, M., and H. H.  Hilger. 2004. ?The systematic position of Ehretia cortesia nom. nov. (= Cortesia cuneifolia: Ehretiaceae, Boraginales) inferred from molecular and morphological data?. Taxon 53:919?923.

Selvi, F., M.  Bigazzi, H. H.  Hilger, and A.  Papini. 2006. ?Molecular phylogeny, morphology and taxonomic re-circumscription of the generic complex {Nonea/Elizaldia/Pulmonaria/Paraskevia} (Boraginaceae-Boragineae)?. 55:907?918.

Hilger, H. H., and E.  Zippel. 2001. ?{"Studies} in the Boraginaceae" - an index to the publications of Ivan M. Johnston dealing with the borage familiy?. 11:1?151.