Find the error in the following paragraph.

According to Taylor et al$.,$to increase reach, the next optimization strategy might be to add the use of targeted Facebook advertisements, followed by using both targeted Facebook and Google advertisements$($p$.2).$ While Facebook and Google advertisements may be effective, they can also be quite pricey. Alternate approaches, such as web$-$based screening and direct emails, may be used to increase outreach $($Taylor et al$.,2020).$