TY - CHAP A1 - Nixdorf, Brigitte A1 - Knopf, K. A1 - Hoehn, Eberhard A1 - Mischke, Ute ED - Karttunen, Krister T1 - Phytoplankton monitoring, classification and assessment in German lakes and rivers present state and problems T2 - Monitoring and assessment of ecological status of aquatic environments Copenhagen Y1 - 2001 SN - 92-893-0667-X SP - 11 EP - 18 PB - Nordic Council of Ministers CY - Copenhagen ER -