W. A.  Coolen, Decraemer, W., Hendrickx, G. J., and Demeyer, P., ?PRESENCE AND RANGE OF VIRUS-TRANSMITTING NEMATODES IN REGIONS DESIGNATED FOR CULTIVATION OF SEED POTATOES IN WESTERN AND EASTERN FLANDERS?, Revue de l AgricultureRevue de l Agriculture, vol. 33, pp. 337-341, 1980.