Geomagnetic data 1957 indices K and C rapid variations /
by J. Bartels, A. Romana and J. Veldkamp
- Amsterdam : North-Holland, 1961
- x, 281 p. : ill. ; 24 cm.
- International association of geomagnetism and aeronomy bulletin ; no. 12 l .
International association of geomagnetism and aeronomy formaly known as association of terrestrail magnetism and electricity