Geomagnetic indices k and c, 1954
Bartels, J
Geomagnetic indices k and c, 1954 J. Bartels and J Veldkemp - Washington 1955
Geomagnetic indices
083.550.38 / IAGA-12I
Geomagnetic indices k and c, 1954 J. Bartels and J Veldkemp - Washington 1955
Geomagnetic indices
083.550.38 / IAGA-12I