TY  - JOUR
AU  - D. Bienstock
TI  - Some Provably Hard Crossing Number Problems.
JO  - Discrete & computational geometry
PY  - 1991
SP  - 443
EP  - 460
VL  - 6
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DCG_1991__6_4_131170/
ID  - DCG_1991__6_4_131170
ER  -