- "Protection of the Coastal Wetland Area - Matsalu Catchment Area" : Estonian-Swedish Joint ProjectFrisen, Rune; Velner, Harald-Adam; Loigu, Enn; Blinova, Irina; Leisk, Ülle; Suurkask, Valdu; Iital, Arvo; Lääne, Ain; Merisaar, Maret; Krutova, Svetlana1995 https://www.ester.ee/record=b1465942*est
- Protection of the coastal wetland area : (Matsalu example)Frisen, Rune; Thorell, L.; Loigu, Enn; Velner, Harald-Adam"Environmental Impact and Water Management in a Catchment Area Perspective" : 24-26 September, 2001, Tallinn, Estonia : proceedings of the Symposium dedicated to the 40th Anniversary of Institute of Environmental Engineering at Tallinn Technical University2001 / p. 113-116 : map