M15
Zaide, Gregorio F.  Pageant of Philippine History: Political, Economic, and Socio-Cultural. Volume 1 From prehistory to the eve of the British invasion. Philippine Education Co. Manila. 1979

Zaide, Gregorio F. & Sonia M. Zaide. History of the Republic of the Philippines, revised college edition, 1987. p. ix. ISBN 971-08-3995-0 Published by National Book Store Inc.
In the postscript to this edition on page ix, Sonia Zaide refers to revisions made to the original edition published in 1983:

"Previous users of this book...will notice there have been many changes. Among the most noteworthy changes [is the]... deletion of the historical notes from the Maragtas and Kalantiaw Code, since both appear to be 20th century creations".

Zaide, Gregorio F. & Sonia M. Zaide. Philippine History, corrected edition. 1987. preface ISBN 971-08-3873-3 Published by National Book Store Inc.
In the preface to this edition, Sonia Zaide listed the revisions made to the original edition published in 1984:

"(3) Correction of the historical interpretation of the role of Panay (a legend), the Confederation of Madya-as (fiction), the legal codes of Datu Kalantiao and Sumakwel (fakes)..."