Walczak, N., M. Hammerling, J. Bykowski, and Z. Walczak. “Economic and Hydraulic Criteria for Maintenance of Good Condition of Drainage Ditches”. Journal of Agribusiness and Rural Development, Vol. 35, no. 1, Dec. 2015, pp. 137-46, doi:10.17306/JARD.2015.15.