Conversation so far:
What type of work did Lillian do?
For more than forty years, Gilbreth's career combined psychology with the study of scientific management and engineering.
What other type of work did she do?
In addition to jointly running Gilbreth Incorporated, their business and engineering consulting firm, Lillian and Frank wrote numerous publications as sole authors.

Question: What type of books did she write?
Self-contained rewrite: What type of books did Lillian Moller Gilbreth write?