XLIV. Letter from M. Kreil, director of the observatory at Milan, to M. Kupffer, director general of the physical observatories in Russia, containing a succinct account of the principal results of M. Kreil's magnetic observations at Milan
"XLIV. Letter from M. Kreil, director of the observatory at Milan, to M. Kupffer, director general of the physical observatories in Russia, containing a succinct account of the principal results of M. Kreil's magnetic observations at Milan." The London Edinburgh and Dublin Philosophical Magazine and Journal of Science 16.103 (1840) 241-250