Spagnolo, M.; Clark, C.D.; Hughes, A.L.C.; Dunlop, P.; Stokes, C.R. (2010). «The planar shape of drumlins». Sedimentary Geology. 232: 119–129. doi:10.1016/j.sedgeo.2010.01.008.
Clark, C.D.; Anna L.C. Hughes; Sarah L. Greenwood; Matteo Spagnolo; Felix S.L. Ng (2009). «Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws». Quaternary Science Reviews. Elsevier Ltd. 28: 677–692. Bibcode:2009QSRv...28..677C. doi:10.1016/j.quascirev.2008.08.035.
Clark, C.D.; Anna L.C. Hughes; Sarah L. Greenwood; Matteo Spagnolo; Felix S.L. Ng (2009). «Size and shape characteristics of drumlins, derived from a large sample, and associated scaling laws». Quaternary Science Reviews. Elsevier Ltd. 28: 677–692. Bibcode:2009QSRv...28..677C. doi:10.1016/j.quascirev.2008.08.035.