Q. How do I do the intext citation in MLA style for a book with more than one author?

If the book has three or fewer authors, list their last names separated by commas, both in text and in the parenthetical citation.

For four or more authors, list the first author followed by et al.

For examples, visit Purdue Owl's MLA guide, and select In Text-Citations: the Basics in the left hand column. Look for the entry with one book with multiple authors.