El segundo sexo
Simone de Beauvoir, an important existentialist who spent much of her life as Sartre's partner, wrote about feminist and existentialist ethics in her works, including "The Second Sex" and "The Ethics of Ambiguity". Although often overlooked due to her relationship with Sartre, de Beauvoir integrated existentialism with other forms of thinking such as feminism, unheard of at the time, resulting in alienation from fellow writers such as Camus.