- A D D Craik,
*Mr Hopkins' Men: Cambridge Reform and British Mathematics in the*19*th Century*(Cambridge 2007)**Articles:** - Henry Watson,
*Nature*22 Jan 1903.

- Obituary in
*The Times*

- Henry William Watson,
*Dictionary of National Biography, Second Supplement*Vol**III**(London, 1913), 605.

See THIS LINK.

- D G Kendall, Branching processes since 1873,
*J. London Math. Soc.***41**(1966), 385-406.

- D G Kendall, Branching processes since 1873, in M G Kendall and R L Plackett (eds.),
*Studies in the History of Statistics and Probability***II**(London, 1977), 383-405.