TY  - JOUR
AU  - Barrett, John H.
TI  - Matrix systems of second order differential equations
JO  - Portugaliae mathematica
PY  - 1955
SP  - 79
EP  - 89
VL  - 14
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/PORMA_1955__14_3_114755/
LA  - en
ID  - PORMA_1955__14_3_114755
ER  -