How to cite research paper multiple authors?

Two authors List by their last names and initials. Use the ampersand instead of "and."

3 authors List by last names and initials; commas separate author names, while the last author name is preceded again by ampersand.

more than seven authors List by last names and initials; commas separate author names. After the sixth author's name, use an ellipses in place of the author names. Then provide the final author name. There should be no more than seven names.