@article{AM2_1987__34_137244,
     author = {D. Laugwitz},
     title = {Hidden lemmas in the early history of infinite series.},
     journal = {Aequationes mathematicae},
     pages = {264--276},
     year = {1987},
     volume = {34},
     zbl = {0631.01014},
     url = {http://geodesic.mathdoc.fr/item/AM2_1987__34_137244/}
}