1. Dodgson , op. cit., folio 87.
2. Condensation of Determinants, being a new and brief Method for computing their arithmetical values;Dodgson;Proceedings of the Royal Society of London,1867
3. Dodgson C.L. , Private Journal; unpublished, British Library, 5
4. Dodgson , op. cit., folio 71.