Borealʹnye ︠i︡urskie ammonity (Dorsoplanitinae) i zonalʹnoe raschlenenie volzhskogo ︠i︡arusa - Mikhaĭlov, Nikolaĭ Petrovich (Trudy (Geologicheskiĭ institut (Akademi︠i︡a nauk SSSR)) ;, 1966)