Labor code of the Philippines with amendments presidential decree no. 442 as amended by presidential decrees nos. 570-A, 626, 643, 823, 849, 850, 865-A, 891, 1367, 1368, 1391, 1412, 1641, 1691, 1692, 1693, and Batas Pambansa Blg. 32, 70, 130 and 227. (Institute of Labor and Manpower Studies, 1982)