[3] Her mother, Aletta Kaiser, took care of the children and household, did charity work, and was heavily involved with the local women's suffrage movement.

[4] On 22 December 1910, Berta Lorentz married Wander Johannes de Haas, who would become professor of experimental physics in Leiden, and they went on to have two sons and two daughters.

[8] After defending her doctoral dissertation in Leiden, De Haas-Lorentz taught physics at the Technical University of Delft and translated some of her father's works into German.

[10] During her thesis work, she was the first to carry out a theoretical analysis of thermal fluctuation of electrons in electrical circuits, predating the experimental discovery of the Johnson–Nyquist noise.

[10] In collaboration with her husband, the De Haas couple showed that experiments carried by James Clerk Maxwell failed to prove the hypothesis of André-Marie Ampère, that magnetism in matter is caused by microscopic current loops.