TY  - JOUR
AU  - Willett, D.
TI  - Generalized de la Vallée Poussin Disconjugacy Tests for Linear Differential Equations(1)
JO  - Canadian mathematical bulletin
PY  - 1971
SP  - 419
EP  - 428
VL  - 14
IS  - 3
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CMB-1971-073-3/
DO  - 10.4153/CMB-1971-073-3
ID  - 10_4153_CMB_1971_073_3
ER  -