TY  - JOUR
AU  - Henning, H.B.
TI  - Series approximations to powers of $\pi $
JO  - Portugaliae mathematica
PY  - 1973
SP  - 171
EP  - 177
VL  - 32
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/PORMA_1973__32_3_115205/
LA  - en
ID  - PORMA_1973__32_3_115205
ER  -