During many years, N C Schenck; Yvonne Pérez 1990 Manual for the identification of VA mycorrhizal fungi has been used with that purpose. You can use also Błaszkowski J (2012) Glomeromycota. W. Szafer Institute of Botany, Polish Academy of Sciences, Kraków. You can check the very useful INVAM´s web page: http://invam.caf.wvu. or Web page of Dr. Janusz Blaszkowski: www.agro.ar.szczecin.pl/~jblaszkowski