4. Libri, _Histoire des Sciences Mathématiques en Italie_. Several
places. Bactulica. Paris, 1838-1841. 4 tomes. 8vo.
5. Peacock (Dean of Ely), "Arithmetic," in the _Encyclopædia
Metropolitana_. This is now, I believe to be had either separately, or
in the volume devoted to pure "Mathematics."
6. De Morgan, _Penny Cyclopædia_ in loc., and occasionally elsewhere in
the work.