1. Key to the genera of Lycieae
    Hunziker, A.T. 2001. Genera Solanacearum. A.R.G. Gantner Verlag K.-G. Argentina


  3. Key to the African Lycium species
    Venter, A.M. 2000. Taxonomy of the genus Lycium L. (Solanceae) in Africa. Ph.D. thesis, Department of Botany and Genetics, University of the Orange Free State, Bloemfontein, South Africa.


  5. Link to Lycium in the Flora of China


  7. Key to the South American Lycium species
    Bernardello, L. M. 1986. Revisión taxonónomica de las especies sudamericanas de Lycium (Solanaceae).  Boletín de la academia nacional de ciencias Córdoba 57:173-356.


  9. Key to the North American Lycium species
    Chiang-Cabrera, F. 1981. A taxonomic study of the North American species of Lycium(Solanaceae). Ph.D. thesis, Department of Botany, University of Texas, Austin, U.S.A.


  11. Key to the western hemisphere Lycium species
    Hitchcock, C.L. 1932. A monographic study of the genus Lycium of the western hemisphere.  Annals of the Missouri Botanical Garden 19:179-374.


  13. Link to Key to Lycium of California