@article{1178245674, author = {Tsuchikura, Tamotsu}, title = {On the functions ${\rm Ci}(x,y)$ and ${\rm Si}(x,y)$}, journal = {Tohoku Math. J. (2)}, volume = {2}, number = {2}, year = {1950}, pages = { 68-73}, language = {en}, url = {http://dml.mathdoc.fr/item/1178245674} }
Tsuchikura, Tamotsu. On the functions ${\rm Ci}(x,y)$ and ${\rm Si}(x,y)$. Tohoku Math. J. (2), Tome 2 (1950) no. 2, pp. 68-73. http://gdmltest.u-ga.fr/item/1178245674/