@book{404203, title = {Trigonometrie}, series = {GDML\_Books}, publisher = {P\v r\'\i rodov\v edeck\'e nakladatelstv\'\i }, address = {Praha}, year = {1952}, language = {cs}, url = {http://dml.mathdoc.fr/item/404203} }
Urban, Alois. Trigonometrie. GDML_Books (1952), http://gdmltest.u-ga.fr/item/404203/