Morphologische Untersuchungen auf dem Gebiete der indogermanischen Sprachen 6 Volume Set

Hermann Osthoff (1847-1909) and Karl Brugmann (1849-1919) were central figures in the circle of German scholars who rejected a doctrinal approach to the study of linguistics.

They came to be known as the Neogrammarian school. At the core of their work was the theory that European languages, together with a subset of languages found in central and southern Asia, have a common origin in a single prehistoric language.

They called this ancestor Indo-Germanic (known today as Indo-European) and claimed that its descendants are all related to one another by varying degrees of closeness.

This six-volume elaboration of this thesis was published between 1878 and 1910.