When we reference a source directly (following a preposition like in, from, by or to), we just give the author name and put the year in brackets. If there are two authors: Borgen and Jones (1999); more than two: Borgen et al. (1999)
When there are more than two authors, use "et al." after the first author.
If there are only two authors, give both names separated by "and"
When you cite multiple references, put them in the brackets in chronological (year) order separated by semi colons.
This is another example of a direct citation. A common mistake is to do the citation as follows "Adapted from (Smithers, 2005)"