TY  - JOUR
AU  - Sigbjorn Halvorsen
TI  - On the Quadratic Integrability of Solutions of d2x/dt2 + f(t)x = 0.
JO  - Mathematica Scandinavica
PY  - 1964
SP  - 111
EP  - 119
VL  - 14
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MS2_1964__14_165873/
ID  - MS2_1964__14_165873
ER  -