1. Blencowe & Broadbent, Rep. Rothamsted exp. Stn 1956: 105, 1957.
  2. Broadbent & Heathcote, Ann. appl. Biol. 46: 585, 1958.
  3. Hollings & Stone, Zentbl. Bakt. ParasitKde, Abt II 123: 237, 1969.
  4. Lister, Pl. Path. 7: 144, 1958.
  5. Martini, Proc. 3rd conf. Potato Virus Diseases, Lisse-Wageningen, 1957: 106, 1958.