@article{JMPA_1939_9_18__217_0,
     author = {Thomas, T. Y. and Titt, E. W.},
     title = {On the elementary solution of the general linear differential equation of the second order with analytic coefficients},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {217--248},
     publisher = {Gauthier-Villars},
     volume = {Ser. 9, 18},
     year = {1939},
     mrnumber = {730},
     zbl = {0023.03901},
     language = {en},
     url = {http://archive.numdam.org/item/JMPA_1939_9_18__217_0/}
}