Hillier R, Edwards D, Morrissey LB (2008). "Sedimentological evidence for rooting structures in the Early Devonian Anglo–Welsh Basin (UK), with speculation on their producers". Palaeogeography, Palaeoclimatology, Palaeoecology. 270 (3–4): 366–380. Bibcode:2008PPP...270..366H. doi:10.1016/j.palaeo.2008.01.038.
Hillier R, Edwards D, Morrissey LB (2008). "Sedimentological evidence for rooting structures in the Early Devonian Anglo–Welsh Basin (UK), with speculation on their producers". Palaeogeography, Palaeoclimatology, Palaeoecology. 270 (3–4): 366–380. Bibcode:2008PPP...270..366H. doi:10.1016/j.palaeo.2008.01.038.
Retallack GJ (1986). "The fossil record of soils"(PDF). In Wright VP (ed.). Paleosols: their Recognition and Interpretation. Oxford: Blackwell. pp. 1–57. Archived(PDF) from the original on 2017-01-07.
Retallack GJ (1986). "The fossil record of soils"(PDF). In Wright VP (ed.). Paleosols: their Recognition and Interpretation. Oxford: Blackwell. pp. 1–57. Archived(PDF) from the original on 2017-01-07.