MLA

Pius II, Pope, 1405-1464, author. Aeneae siluii poaetae laureati, in hystoria[m] de duobus ama[n]tibus p[rae]fatio prima ad perq[uam] generosum milite[m] Casparem Slik foeliciter incipit. [1472]. https://collections.library.yale.edu/catalog/33433886.

APA, 6th edition

Pius II, Pope, 1405-1464, author. ([1472])[Aeneae siluii poaetae laureati, in hystoria[m] de duobus ama[n]tibus p[rae]fatio prima ad perq[uam] generosum milite[m] Casparem Slik foeliciter incipit]. https://collections.library.yale.edu/catalog/33433886.