1. Callahan, Phytopathology 47: 5, 1957a.
  2. Callahan, Diss. Abstr. 17: 1861, 1957b.
  3. Cropley, Nature, Lond. 188: 875, 1960.
  4. Cropley, Ann. appl. Biol. 49: 524, 1961.
  5. Cropley, Ann. appl. Biol. 53: 333, 1964.
  6. Flegg, Rep. E. Malling Res. Stn for 1968: 155, 1969.
  7. Fritzsche & Kegler, Naturwissenschaften 51: 299, 1964.
  8. Fulton & Fulton, Phytopathology 60: 114, 1970.
  9. Hansen, Phytopathology 57: 813, 1967.
  10. Hansen & Stace-Smith, Phytopathology (in press).
  11. Jones & Murant, Ann. appl. Biol. (in press).
  12. Lister & Murant, Ann. appl. Biol. 59: 49, 1967.
  13. Posnette & Cropley, Rep. E. Malling Res. Stn for 1954: 126, 1955.
  14. Schmelzer, Phytopath. Z. 55: 317, 1966.
  15. Stace-Smith, Virology 29: 240, 1966.
  16. Stefanac, Acta bot. croat. 28: 373, 1969.
  17. Tomlinson & Walkey, Ann. appl. Biol. 59: 415, 1967.
  18. Varney & Moore, Phytopathology 42: 476, 1952.
  19. Walkey, Fitzpatrick & Woolfitt, J. gen. Virol. 5: 237, 1969.
  20. Walkey & Webb, J. gen. Virol. 7: 159, 1970.