TY  - JOUR
AU  - H. Lonka
AU  - O. Tammi
TI  - On the use of step-functions in extremum problems of the class with bounded boundary rotation
JO  - Annales Fennici Mathematici
PY  - 1968
VL  - 411-420
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1968.418/
DO  - 10.5186/aasfm.1968.418
LA  - en
ID  - AFM_1968_411-420_a2
ER  -