Medical Center of South Arkansas Adds Four Doctors (Movers & Shakers) by Arkansas Business Staff Posted 1/7/2019 12:00 am Dr. Mark Gibbs, Dr. Anthony Abraham, Dr. Martha Garrett-Shaver and Dr. Samuel Vallery have all joined the staff of the Medical Center of South Arkansas in El Dorado. Want the Full Article? Get Unlimited Archive Access for $19.95 per Year Readers must pay to access articles older than 15 days. Articles newer than 15 days are not included in this offer. Purchase Now Already have archive access? Login to view this article.