About Herman Bouwer.
D000383:Agriculture; D003247:Conservation of Natural Resources; D004738:Engineering; D005844:Geology / Q000266:history*; D049673:History, 20th Century; D006801:Humans; D009426:Netherlands; D011157:Population Dynamics; D012722:Sewage; D012822:Silicon Dioxide; D014881:Water Supply / Q000266:history*
D012722:Sewage; D012822:Silicon Dioxide