TY  - RPRT
TI  - International geomagnetic reference field 1980; charts and grid values
AU  - Eugene B. Fabiano
AU  - N.W. Peddie
AU  - D.R. Barraclough
AU  - A.K. Zunde
PY  - 1983
DO  - 10.3133/cir873
UR  - https://pubs.usgs.gov/publication/cir873
ID  - cir873
ER  -