@inbook{401671,
     title = {2 Elementary properties of integrals of the differential equuation (q)},
     booktitle = {Linear Differential Transformations of the Second Order},
     series = {GDML\_Books},
     publisher = {The English Universities Press, Ltd.},
     address = {London},
     year = {1971},
     pages = {[11]-16},
     url = {http://dml.mathdoc.fr/item/401671}
}