Is the destabilisation of Lake Peipsi ecosystem caused by increased phosphorus loading or decreased nitrogen loading?Nõges, Tiina; Laugaste, Reet; Loigu, Enn; Nedogarko, I.; Skakalski, Boris; Nõges, PeeterWater science & technology Water science and technology2005 / 3/4, p. 267-274 : ill