I am a newbie in LaTeX and I have a significant problem in my work: I need to write a document with bibliography. My problem is that I have different languages items in the bibliogrpahy, and I need to use different bibliogrpahy style for different languages. My idea is that I need to use thebibliography environment to solve this. It is working, but I need to use textual citations in the text (e.g. (Einsten, 1922), Harvard citation style). How can I make textual citations in accordance with thebibliography environment? (I saw natbib, bibtex and biblatex but in these environments I can not make items in the bibliography with different styles...)
Thanks for the help!

biblatexso you should not have to resort to a manual bibliography to do this. See biblatex: per-entry language switching – Alan Munn Jul 30 '17 at 13:48