TY  - RPRT
TI  - The geomagnetic jerk of 1969 and the DGRFs
AU  - D. Thompson
AU  - J.C. Cain
PY  - 1987
DO  - 10.1016/0031-9201(87)90163-4
UR  - https://pubs.usgs.gov/publication/70014204
ID  - 70014204
ER  -