Leal, M. E., and V. B. de Sant-Anna. “Quantitative Analysis of Interspecific and Ontogenetic Variation in Osteoglossum Species (Teleostei: Osteoglossiformes: Osteoglossidae)”. Zootaxa, vol. 1239, no. 1, June 2006, pp. 49–68, doi:10.11646/zootaxa.1239.1.4.