Validation of High-Performance Liquid Chromatography for Determination of Bromelain in Pineapple (Ananas comosus (L) Merr) Water, Yantih, Novi, Methananda Alfadella, Harahap Yahdiana, Sumaryono Wahono, and Rahayu Lestari , Pharmacognosy Journal, September 2019, Volume 11, Issue 5, p.901-906, (2019)