1. Conti, Phytopath. Z. 66: 275, 1969.
  2. Hills & Campbell, J. Ultrastruct. Res. 24: 134, 1968.
  3. Howatson, Adv. Virus Res. 16: 196, 1970.
  4. Hull, in Biology of Large RNA Viruses, ed. R. D. Barry & B. W. J. Mahy, Academic Press, N.Y., 1970.
  5. Lin & Campbell, Virology 48: 30, 1972.
  6. McLean & Francki, Virology 31: 585, 1967.
  7. Tomlinson & Webb, Rep. natn. Veg. Res. Stn 1970: 110, 1971.
  8. Tomlinson, Webb & Faithfull, Ann. appl. Biol. 71: 127, 1972.