1. Barragán, T., Esteve, J., García-Bellido, D.C., et al., Hadimopanella oezgueli Gedik, 1977: A palaeoscolecidan sclerite useless for taxonomic purposes, Palaeontol. Electronica, 2014a, 17.3.42A, pp. 1–20.
2. Barragán, T., Esteve, J., García-Bellido, D.C., et al., New Middle Cambrian palaeoscolecid sclerites of Hadimopanella oezgueli from the Cantabrian Mountains, northern Spain, GFF, 2014b, vol. 136, pp. 22–25.
3. Bengtson, S., Aspects of problematic fossils in the Early Palaeozoic, Acta Univ. Uppsal. Abstr. Diss. Fac. Sci., 1977, vol. 415, pp. 1–71.
4. Conway Morris, S. and Robison, R.A., Middle Cambrian priapulids and other soft-bodied fossils from Utah and Spain, Paleontol. Contrib. Univ. Kansas Papers, 1986, vol. 117, pp. 1–22.
5. Conway Morris, S., The cuticular structure of the 495-Myr-old type species of the fossil worm Palaeoscolex, P. piscatorum (?Priapulida), Zool. J. Linn. Soc., 1997, vol. 119, pp. 69–82.