MLA Style:

MLA Style at Excelsior OWL: https://owl.excelsior.edu/citation-and-documentation/mla-style/

MLA Style Center: https://style.mla.org

MLA Works Cited: https://style.mla.org/works-cited/citations-by-format/

Formatting a Paper in MLA Style: https://style.mla.org/formatting-papers/

APA Style:

APA Style Online Handbook: https://apastyle.apa.org 

APA Style at Excelsior OWL: https://owl.excelsior.edu/citation-and-documentation/apa-style/

Chicago Manual of Style:

Chicago Manual of Style Online: https://www.chicagomanualofstyle.org/home.html

Chicago Style at Excelsior OWL: https://owl.excelsior.edu/citation-and-documentation/chicago-style/

Other Helpful Links:

Tips & Tools: UNC Chapel Hill Writing Center: https://writingcenter.unc.edu/tips-and-tools/ 

Excelsior OWL: https://owl.excelsior.edu

Purdue OWL: https://owl.purdue.edu

Writing Commons: https://writingcommons.org