Influence of Extraction Parameters on the Yield, Phytochemical, TLC-Densitometric Quantification of Quercetin, and LC-MS Profile, and how to Standardize Different Batches for Long Term from Ageratum conyoides L. Leaves, Tambunan, Anita Paulina, Bahtiar Anton, and Tjandrawinata Raymond Rubianto , Pharmacognosy Journal, September 2017, Volume 9, Issue 6, p.767-774, (2017)