@article{JRAM_1880__89_183434,
     author = {G. Hettner},
     title = {Zur {Theorie} des arithmetisch-geometrischen {Mittels} aus vier {Elementen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {221--246},
     publisher = {mathdoc},
     volume = {89},
     year = {1880},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1880__89_183434/}
}