Authors Year Title
Becker & House 1994 International Devonian goniatite zonation, Emsian to Givetian, with new records from Morocco.
Courier Forschungsinstitut Senckenberg 169: 79-135, 10 text-figs., 7 pls., Frankfurt am Main.
Bultynck_&_Walliser & Walliser 1991 Proposal for the Eifelian/Givetian Stratotype in Southern Morocco.
Document submitted Subcommission Devonian Stratigraphy Frankfurt 1990, 3 pp.