Boshondstong - Cynoglossum germanicum

English Botany, or Coloured Figures of British Plants, deel 7, J.E. Sowerby (1867)

Illustrations of the British Flora, Walter Hood Fitch (1924)

Ecphrasis minus cognitarum stirpium, deel 1, F. Colonna (1616)

Cynoglossa media montana rubro flore