Many electronic journals do not have actual page numbers - - they provide an "article number" instead of page numbers.
In APA Style - here is an example of how to cite it:
Jerrentrup, A., Mueller, T., Glowalla, U., Herder, M., Henrichs, N., Neubauer, A., & Schaefer, J. R. (2018). Teaching medicine with the help of “Dr. House.” PLoS ONE, 13(3), Article e0193972. https://doi.org/10.1371/journal.pone.0193972
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