MLA

Varro, Marcus Terentius. De Lingua Latina. 0AD. https://collections.library.yale.edu/catalog/11403218.

APA, 6th edition

Varro, M. T. (0 C.E.). De lingua latina [Manuscripts, Medieval Italy 15th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/11403218.