Lang, C. L. (2007). Fries - Gellert. De Gruyter.
Lua i Stíl Chicago (17ú heag.)Lang, Carl Ludwig. Fries - Gellert. Berlin [u.a.]: De Gruyter, 2007.
Lua MLA (8ú heag.)Lang, Carl Ludwig. Fries - Gellert. De Gruyter, 2007.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.