Asri, M. N. M., W. N. S. M. Desa, and D. Ismail. “Fourier Transform Infrared (FTIR) Spectroscopy With Chemometric Techniques for the Classification of Ballpoint Pen Inks”. Arab Journal of Forensic Sciences & Forensic Medicine , vol. 1, no. 2, Dec. 2015, doi:10.12816/0017699.