1. Berkenhamp, Canadian Plant Disease Survey 51: 96?100, 1971
2. Smith, Blyttia 34: 99?102, 1976
3. ?, Bulletin of the Research Institute Neori As, Hverageroi, Iceland 32: 1?12, 1980
4. Smith & Elliott, Canadian Plant Disease Survey 52: 39?41, 1972
5. Smith, Elliott & Shoemaker, Canadian Plant Disease Survey 48: 115?119, 1968