Encyclopediaof Chemical Technology။ Wiley။ pp. 343–383။ doi:10.1002/0471238961.0701190508230114.a01။ ISBN 0-471-23896-1။ Magnetic susceptibility of the
University of Chicago Press။ pp. 8–9။ ISBN 0-226-05641-4။ Davies၊ S.J.J.F. (2003)။ "Rheas"။ in Hutchins၊ Michael (ed.)။ Grzimek's Animal LifeEncyclopedia။ 8: