Victoriano R. Ragasa, and Ronald Amano. “The Manufacture of Tiles (l/4"x4‘x4’) Using Vigan Clay, Silica, and Ball Clay”. The Vector: International Journal of Emerging Science, Technology and Management (IJESTM), vol. 7, no. 1, Dec. 1998, doi:10.69566/ijestm.v7i1.123.