Smyth, Herbert Weir (1920). "Part I: Letters, Sounds, Syllables, Accent". A Greek Grammar for Colleges. Cambridge, Massachusetts: American Book Co. § 62.
Smyth, Herbert Weir (1920). "Part II: Inflection". A Greek Grammar for Colleges. Cambridge, Massachusetts: American Book Co. § 197.
Smyth, Herbert Weir (1920). "Part II: Inflection". A Greek Grammar for Colleges. Cambridge, Massachusetts: American Book Co. § 195.