Prochazka, P., Reif, J., Horak, D., Klvana, P., Lee, R. W., & Yohannes, E. (2010). Using stable isotopes to trace resource acquisition and trophic position in four Afrotropical birds with different diets. Ostrich, 81(3), 273-275. doi:10.2989/00306525.2010.519889.