Browne, C. A., « Bernhard Tollens (1841-1918) and Some American Students of his School of Agricultural Chemistry », Journal of Chemical Education, vol. 19, no 6, , p. 253–259 (DOI10.1021/ed019p253, Bibcode1942JChEd..19..253B).
harvard.edu
ui.adsabs.harvard.edu
Browne, C. A., « Bernhard Tollens (1841-1918) and Some American Students of his School of Agricultural Chemistry », Journal of Chemical Education, vol. 19, no 6, , p. 253–259 (DOI10.1021/ed019p253, Bibcode1942JChEd..19..253B).