Sandra Stanley Holton, Clark, Hilda (1881–1955), Physician and Humanitarian Aid Worker. Oxford Dictionary of National Biography (2016; repr., Oxford 2004), doi:https://doi.org/10.1093/ref:odnb/38518.

Sandra Stanley Holton, Quaker Women. Personal Life, Memory and Radicalism in the Lives of Women Friends, 1780–1930 (London 2007).

Sandra Stanley Holton, Suffrage Days. Stories from the Women’s Suffrage Movement (London 1996).