Thomas A. Carlson (eds.), "Yoḥannan bar Abgare" in The Gorgias Encyclopedic Dictionary of the Syriac Heritage last modified September 4, 2013, http://syriaca.org/bibl/604
    
        
            
                
                    
                        H.
                        Kaufhold 
                    
                    Yoḥannan bar Abgare
                
        
                
                    
                        
                            Sebastian
                            P.
                            Brock
                        
                    
                    
                        
                            Aaron
                            M.
                            Butts
                        
                    
                    
                        
                            George
                            A.
                            Kiraz
                        
                    
                    
                        
                            Lucas
                            Van Rompay
                        
                    
                    The Gorgias Encyclopedic Dictionary of the Syriac Heritage
                    http://syriaca.org/bibl/1
                    
                        Gorgias Press
                        Piscataway, NJ
                        
                        2011
                    
                    439-440
                
                http://syriaca.org/bibl/604