Falcis, C. T., Herrin, M. A., & Varona, A. J. (2000). A methods engineering study of Progressive Laboratories, Inc. College of Engineering, University of the Philippines Diliman, Quezon City.

Falcis, Charlene Therese, Mark Andrew Herrin, and Andrew James Varona. A Methods Engineering Study of Progressive Laboratories, Inc. Department of Industrial Engineering and Operations Research: College of Engineering, University of the Philippines Diliman, Quezon City, 2000.

Falcis, Charlene Therese, et al. A Methods Engineering Study of Progressive Laboratories, Inc. College of Engineering, University of the Philippines Diliman, Quezon City, 2000.