TY  - JOUR
AU  - Preiss, David
TI  - Approximate derivatives and Baire classes
JO  - Czechoslovak Mathematical Journal
PY  - 1971
SP  - 373
EP  - 382
VL  - 21
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1971.101037/
DO  - 10.21136/CMJ.1971.101037
LA  - en
ID  - 10_21136_CMJ_1971_101037
ER  -