*Lathan A. Windley, ''[http://www.worldcat.org/oclc/9217777 Runaway Slave Advertisements: a Documentary History from the 1730s to 1790]'', 4 v. (Westport, Conn.: Greenwood Press, 1983). Contents: Vol. 1. Virginia and North Carolina -- v. 2. Maryland -- v. 3. South Carolina -- v. 4. Georgia.
It is difficult to find an ancestor in runaway slave advertisements. In order to use these records you need to know the name of the slave, and it is also important to know the owner's name to help identify the correct slave. It would also help to know where the owner lived in order to determine if there are nearby newspapers with compiled runaway slave advertisements. There were many newspapers in which owners could have advertised, so coverage is spotty.
*[https://www.accessible-archives.com/collections/african-american-newspapers/ Accessible Archives - African American Newspapers]
*[https://www.digitalcommonwealth.org/collections/commonwealth:ht24xg10q "The Liberator," an abolitionist newspaper published 1831-1866]