The Secular Variation of Components of the Geomagnetic Field as Measured at Hong Kong from 1884-1973

M. R. NEIGHBOUR, D. G. RIVERS, G. O. WALKER
1974 Journal of geomagnetism and geoelectricity  
doi:10.5636/jgg.26.443 fatcat:gnokig6pkjaotm5g6jqqfolf4u