At csl.mendeley.com you can find citation styles by entering in-page citation or bibliography format. To find a citation style by example 4 steps:

Steps 1-2-3-4: Go to csl.mendeley.com (1) > Search by example (2) > Enter a sample in-page citation or bibliography format (3) > Search (4) > take note the citation name as “American Psychological Association 6th edition”.

Step 5: When you learn the name of the citation from previous step, you can set this style at Mendeley Reference Manager by using instructions under the title “2) Searching Citations Styles in the Software”.