APA

Engels J., Hawkes J. G. & Worede M. (1991). Plant genetic resources of Ethiopia. Cambridge: Cambridge University Press.

Chicago

Engels J.m.m, Hawkes John Gregory and Worede M. 1991. Plant genetic resources of Ethiopia. Cambridge: Cambridge University Press.

Harvard

Engels J., Hawkes J. G. and Worede M. (1991). Plant genetic resources of Ethiopia. Cambridge: Cambridge University Press.

MLA

Engels J.m.m, Hawkes John Gregory and Worede M. Plant genetic resources of Ethiopia. Cambridge: Cambridge University Press. 1991.