1. Atanasoff, Phytopath. Z. 8: 197, 1935.
2. Berg, Meded. LandbHoogesch. Wageningen 64: 11, 1964.
3. Biddle & Tinsley, New Phytol. 70: 61, 1971a.
4. Biddle & Tinsley, New Phytol. 70: 67,1971b.
5. Blattný, Lesn. Cas. 11: 637, 1965.
6. Boyer, Can. J. Bot. 40: 1237, 1962.
7. Brandes & Wetter, Virology 8: 99, 1959.
8. Schmelzer, Phytopath. Z. 55: 317, 1966.