. . "1919-12-12Z"^^ . . "Paul Gustav Samuel St\u00E4ckel (20 August 1862, Berlin \u2013 12 December 1919, Heidelberg) was a German mathematician, active in the areas of differential geometry, number theory, and non-Euclidean geometry."@en . "German mathematician" . "1919Z"^^ . "1862Z"^^ . . "Stackel, Paul"@en . "1862-08-20Z"^^ .