R. O. Roberts is a volume editor of Trafodion Economaidd a Chymdeithasol 1956-63 and Trafodion Economaidd a Chymdeithasol 1964-73. W. H. R. Davies is a volume editor of Trafodion Economaidd a Chymdeithasol 1964-73. H. Huw R. Davies is a volume editor of Trafodion Economaidd a Chymdeithasol 1964-73.