What does e.d. mean in the end of a citation

I am getting e.d. in the end of some mine citation.

(„Edward L. Thorndike (1874–1949) - The Man and His Career, A Psychology for Educators, Education as Specific Habit Formation“, e.d.)

and

(„Franklin Bobbitt (1876–1956) - Social Efficiency Movement, Bobbitt’s Contribution“, e.d.)

Does anyone know what e.d. stands for?
I am writing mine Master and I am worried I might be doing something wrong that will hurt me later.
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