Home › Authors › Sigurd Olsen 👤 Sigurd Olsen 4 books Books by Sigurd Olsen Introduction to the phosphate Introduction to the phosphate equilibrium between mud and water in Lake Furesø 1966 Lake Lyngby sø 1955 A suggested starting-point for A suggested starting-point for the nomenclature of Charophyta 1949 Danish Charophyta Danish Charophyta 1944