Usually encyclopedias are edited and compiled by editors, with contributors writing the different articles. The entry in the reference list will look like that of a chapter in a collected work.
Conteh-Morgan, J. (2003). Modern drama. In S. Gikandi (Ed.), Encyclopedia of African literature (pp. 332-336). Routledge.
Murphy, J. B., & Van Andel, T. H. (2018). Plate tectonics. In Britannica academic. https://academic-eb-com.nwulib.nwu.ac.za/levels/collegiate/article/plate-tectonics/108555
(Murphy & Van Andel, 2018).