@misc{Schwering_Karl_(1846–1925)_Handbuch_1907, author={Schwering, Karl (1846–1925)}, copyright={Public Domain}, address={Leipzig}, address={Berlin}, howpublished={online}, year={1907}, publisher={B. G. Teubner}, language={ger}, type={Text}, title={Handbuch der Elementarmathematik für Lehrer}, URL={http://rcin.org.pl/impan/Content/67918/PDF/WA35_18216_7091_Handbuch.pdf}, }