TY  - BOOK
AU  - Heiskanen,W.
TI  - Topographic-isostatic reduction maps for europe and north atlantic in the hayford zones 18-1 for the airy-heiskanen system, t= 30 km and 20 km
T2  - Annales Academiae Scientiarum Fennicae ; 
PY  - 1959///
CY  - Helsinki : 
PB  - Suomalainen Tiedeakatemia, 
ER  -