| XXXV.—On the Composition of Chalk Rocks and Chalk Marl by invisible Organic Bodies : from the Observations of Dr. Ehrenberg Thomas Weaver (1841) Annals And Magazine of Natural History 7: 296-315 | |
| XL.—On the Composition of Chalk Rocks and Chalk Marl by invisible Organic Bodies : from the Observations of Dr. Ehrenberg (1841) Annals And Magazine of Natural History 7: 374-398 |