BSL. — 1975. — T. 70. — P. 1–10.
Schindler argues that Indo-European nominal stems with heteroclitic stem alternation r/n could belong to several different inflectional types (accent-ablaut paradigms). The main distinction he established is between collectives with nom.-acc. in -ōr ("holokinetic" / "amphikinetic") and singulars with the suffix in oblique stem forms either in the zero-grade -n- ("acrostatic") or full-grade -en- ("proterokinetic").