Yasin, S., . Adrinal, . Junaidi, E. Wahyudi, S. Herlena, and . Darmawan. “Changes of Soil Properties on Various Ages of Rubber Trees in Dhamasraya, West Sumatra, Indonesia”. JOURNAL OF TROPICAL SOILS, vol. 15, no. 3, Apr. 2018, pp. 221-7, doi:10.5400/jts.2010.v15i3.221-227.