Kelz, H. P. (1978). Language development in Germany: The evolution and standardization of the German language. Institute of National Language.
Lua i Stíl Chicago (17ú heag.)Kelz, Heinrich P. Language Development in Germany: The Evolution and Standardization of the German Language. Manila: Institute of National Language, 1978.
Lua MLA (9ú heag.)Kelz, Heinrich P. Language Development in Germany: The Evolution and Standardization of the German Language. Institute of National Language, 1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.