H. F.  Greeney, Dobbs, R. C., Diaz, G. I. C., Kerr, S., and Hayhurst, J. G., ?Breeding biology of the Green-fronted Lancebill (Doryfera ludovicae) in eastern Ecuador?, Ornitolog{\'?a Neotropical, vol. 17, pp. 321-331, 2006.