Hoffmann, Richard C. (1996). "Economic Development and Aquatic Ecosystems in Medieval Europe". The American Historical Review. 101 (3): 631–669. doi:10.2307/2169418. JSTOR2169418.
Hoffmann, Richard C. (1996). "Economic Development and Aquatic Ecosystems in Medieval Europe". The American Historical Review. 101 (3): 631–669. doi:10.2307/2169418. JSTOR2169418.