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Gottschling, M., N.  Diane, H. H.  Hilger, and M.  Weigend. 2004. ?Testing hypotheses on disjunctions present in the primarily woody Boraginales: Ehretiaceae, Cordiaceae, and Heliotropiaceae, inferred from ITS1 sequence data?. Int. J. Plant Sci. 165:S123?S135.

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., A.  Papini, H. H.  Hilger, M.  Bigazzi, and E.  Nardi. 2004. ?The phylogenetic relationships of Cynoglottis (Boraginaceae-Boragineae) inferred from {ITS}, {5.8S} and {trnL} sequences?. 246:195?209.

Hilger, H. H., F.  Selvi, A.  Papini, and M.  Bigazzi. 2004. ?Molecular systematics of Boraginaceae tribe Boragineae based on {ITS1} and {trnL} sequences, with special reference to Anchusa s.l.?. 94:201?212.