E. O.  Campbell, ?The fungal association in a colony of Gastrodia sesamoides R. Br.?, Trans. Roy. Soc. New Zealand, vol. 2, pp. 237 - 246, 1964.

E. O.  Campbell, ?The mycorrhiza of Gastrodia cunninghamii Hook. f.?, Trans. Roy. Soc. New Zealand, Botany, vol. 1, pp. 289 - 296, 1962.

E. O.  Campbell, ?The morphology of the fungal associations of three species of Corallorhiza in Michigan?, Michigan Bot., vol. 9, pp. 108 - 113, 1970.

E. O.  Campbell, ?Gastrodia minor Petrie, an epiparasite of Manuka?, Trans. Roy. Soc. New Zealand, vol. 2, pp. 73 - 81, 1963.

E. O.  Campbell, ?An investigation of Thismia rodwayi F. Muell. and its associated fungus?, Trans. Roy. Soc. New Zealand, vol. 3, pp. 209 - 219, 1968.

E. O.  Campbell, ?Notes on the fungal association of two Monotropa species in Michigan?, Michigan Bot., vol. 10, pp. 63 - 67, 1971.