van Bavel, B. J. P.  (1999).  A valuation of arable productivity in the central part of the Dutch river area, c.1360-c.1570. In B. J. P.  van Bavel & Thoen, E. (Red.), Land productivity and agro-systems in the North Sea area (Middle Ages - 20th century). Elements for Comparison (Vol. 2, pp. 297-309). Turnhout: Brepols.