Scholar of prints and engravings. Arthur Mayger Hind studied under him in Dresden before joining the prints department at the British Museum. In 1893 Lehrs and Elfried Bock collaborated with the curator of the Kupferstichkabinett of the Berlin State Museums, Friedrich Lippmann, to write an introduction to the history of engraving, Der Kupferstich. It went through many editions and was updated by Lehrs and translated into English by the keeper of the Victorian and Albert Museum, Martin Hardie in 1906.The professor of Art History at Utrecht University, J. G. van Gelder, described Lehrs' work as one of the praiseworthy graphic studies of Netherlandish of the nineteenth and early twentieth centuries.
Geschichte und kritischer Katalog des deutschen, niederländischen, und französichen Kupferstichs, 1908-34, English: Mayor, A. Hyatt, edited. Late Gothic Engravings of Germany & the Netherlands. 682 copperplates from the "Kritischer Katalog." With a new essay "Early engraving in Germany and the Netherlands" New York: Dover Publications, 1969; and Bock, Elfried, and Lippmann, Friedrich. Der Kupferstich. Berlin: W. Spemann, 1893.
Metzler Kunsthistoriker Lexikon: zweihundert Porträts deutschsprachiger Autoren aus vier Jahrhunderten. Stuttgart: Metzler, 1999, pp. 237-9; van Gelder, Jan G. [Forward.] Hollstein, F. W. H. Dutch and Flemish Etchings, Engravings and Woodcuts, ca 1450-1700. vol. 1. Amsterdam: Menno Hertzberger, 1949, p. [i].