Johanna Geertruida (Truus) van Cittert-Eymers (1903–1988) was a Dutch physicist, historian of science, museum director and author.

She graduated from secondary school with a HBS-b diploma in Arnhem in 1921 and moved to Utrecht to begin studying physics at the university there in 1923.

[1] Eymers began work as a researcher in the experimental physics group of Leonard Ornstein at Utrecht University in 1929 and in 1932 became the head of the teaching laboratory.

[3][4] Eymers graduated cum laude with a PhD in 1935 and did postdoctoral research in biophysics, specifically on luminescent bacteria.

[2] The couple had a son, Benjamin, in 1939 who died in infancy and a daughter, Han [ nl ], in 1943 who became a biologist.