Damayanti, Ayu Anisa, 		Trisnawati, Ni Luh Putu, AND 		Suyanto, Hery.
" Identification of Betel Leaf Wave Numbers (Piper sp.) Using Fourier Transform Infrared (FTIR) Spectroscopy Methods and Principal Component Analysis (PCA)" <em>BULETIN FISIKA</em> [Online], Volume 22 Number 2 (7 November 2020)