In Philippine Saga which he wrote with Jaime C. de Veyra in 1947, he mentioned a manuscript from Panay known as Maragtas and “the ancient writing in which it was originally inscribed". M7 Then in his Outline Review of Philippine Archaeology of 1949 he wrote the following:
Sa Philippine Saga na isinulat nilá ni Jaime C. de Veyra noóng 1947, binanggít niyá isáng kasulatan galing sa Panay na tinatawag na Maragtás “at ang antigong pagkákasulat ng orihinál nitó”.M7 At sa kaniyáng Outline Review of Philippine Archaeology ng 1949 isinulat niyá ang sumúsunód: