Kielan-Jaworowska Z. (1966) Polychaete jaw apparatuses from the Ordovician and Silurian of Poland and a comparison with modern forms. Palaeontologia Polonica, 16, 1–152.

Kozur H. (1970) Fossile Hirudinea aus dem Oberjura von Bayern. Lethaia, 3, 225–32.

Little C. T. S. et al. (1999) Two Palaeozoic hydrothermal vent communities from the southern Ural Mountains, Russia. Palaeontology, 42, 1043–78.

Little C. T. S., Danelian T., Herrington R. J., Haymon R. M. (2004) Early Jurassic hydrothermal vent community from the Franciscan Complex, California. Journal of Paleontology, 78, 542–59.

Manum S. B., Bose M. N., Sawyer R. T. (1991) Clitellate cocoons in freshwater deposits since the Triassic. Zoologica Scripta, 20, 347–66.

McLoughlin S., Bomfleur B., Mörs T., Reguero M. (2016) Fossil clitellate annelid cocoons and their microbiological inclusions from the Eocene of Seymour Island, Antarctica. Palaeontologia Electronica, 19.1.11A, 1–27. https://core.ac.uk/download/pdf/326792266.pdf.

Muir, L. A., Botting, J. P. (2007) A Lower Carboniferous sipunculan from the Granton Shrimp Bed, Edinburgh. Scottish Journal of Geology, 43, 51–6.

Nanglu K., Caron J.-B. (2018) A new Burgess Shale polychaete and the origin of the annelid head revisited. Current Biology, 28, 319–26.

Parry L., Tanner A., Vinther J. (2014) The origin of annelids. Palaeontology, 57, 1091–1103.