MLA

de Essendia, Johannes. Tractatus De Spiritu. 1474. https://collections.library.yale.edu/catalog/10621959.

APA, 6th edition

de Essendia, J. (1474). Tractatus de spiritu [Manuscripts, Medieval Germany 15th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/10621959.