Untersuchungen zur Morphologie und Systematik der Vögel, zugleich ein Beitrag zur Anatomie der Stütz- und Bewegungsorgane. 2 vols.

Fürbringer specialized in avian morphology and classification; he undertook the first major phylogenetic ordering of bird groups based on a large scale study of skeletal, morphological and anatomical characteristics. Digital facsimile of the 2 vols. from the Biodiversity Heritage Library at this link.