Speirs, A. G. E. (1973). Proto-Indo-European labio-velars and laryngeals.
Lua i Stíl Chicago (17ú heag.)Speirs, A. G. E. Proto-Indo-European Labio-velars and Laryngeals. Brisbane, 1973.
Lua MLA (8ú heag.)Speirs, A. G. E. Proto-Indo-European Labio-velars and Laryngeals. 1973.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.