1. Graptolites of North America;Ruedemann;Geol. Soc. Amer.,1947
2. Graptoloids from the Ontikan and Viruan (Ordov.) Limestones of Estonia and Sweden;Jaanusson;Bull. geol. Instn.,1960
3. British Graptolites;Elles;Palaeont. Soc. Lond.,1907
4. Graptolites from Anticosti Island