@misc{Jan_XXI_(papież_;_około_1220-1277)_Summulae,
 author={Jan XXI (papież ; około 1220-1277)},
 howpublished={online},
 publisher={Heinrich Gran},
 language={lat},
 title={Summulae logicales : Commentum in I et IV tractatus Parvorum logicalium Petri Hispani et super tractatus Marsilii},
 type={inkunabuł},
}