Lindkvist, Thomas. “ Nils Hybel: Crisis or Change. The Concept of Crisis in the Light of Agrarian Structural Reorganization in Late Medieval England, Aarhus University Press 1989, 333 S”. Historisk Tidsskrift, bd. 15, nr. 1, januar 1991, s. 233-46, doi:10.7146/ht.v15i1.53377.