Czech to English Social Sciences Religion sociology of religion

Dear colleagues,

once again I ask for your help concerning the very same topic of sociology of religion. This time, I am translating information about the author (at the end of the article) and I have been hopelessly trying to understand what the following the "poet wanted to say" (as we say in Czech when something makes very little sense and you've got to look for the meaning as if it were poetry) in the following sentence

The author is a scientific researcher at the Institute of Sociology of the Academy of Sicences, the Czech Republic and an assistant professor at the Faculty of Humanities of the Charles University. ...
"Věnuje se dějinám a sociologii náboženství, příležitostně si k tomu přibírá další témata z historie a sociologie, včetně jejich dějin."

I find this sentence very confusing, especially since "dějiny" and "historie" means essential the same thing and they both translate as "history" in English. The sentence thus does not make sense to me.

One could say: "He focuses in his research on history and sociology. Ocassionaly he also covers other topics ?????" and the sentence stops making sense at this point. I have tried to look at it as "He focused in his research on history of sociology [which is essential what he does in this article] and ocassionaly he also covers other topics from history and sociology, including their???? ... well I am lost again. I am almost tempted to cut some of the information out and simply say that "He focused in his research on history and sociology, including the history of sociology". (full stop) but even that does quite flow in English and sounds rather very awkward.

Thank you!!!
Myska