Internet Encyclopedia of Philosophy
http://www.iep.utm.edu/beauvoir/
More information on de Beauvoir's life and philosophy in general
Becoming A Woman: Simone de Beauvoir on Female Embodiment
https://philosophynow.org/issues/69/Becoming_A_Woman_Simone_de_Beauvoir_on_Female_Embodiment
A more recent review of Simone de Beauvoir's text in relation to existentialist philosophy in general.
Open Culture
An interview with Simone de Beauvoir from 1975 in which she explains her thoughts on feminism.