Note 94 — Chapter XIX · ORIGIN OF GRAMMATICAL ELEMENTS
Reading edition
Cf. Sommer, Lat. 528, and on Armenian and Tokharian r forms MSL 18. 10 ff. and Feist KI 455. But it must not be overlooked that H. Pedersen (KZ 40. 166 ff.) has revived and strengthened the old theory that r in Italic and Keltic is an original se.