@INBOOK {NG:1990a, title = {The role of tissue culture in the establishment of disease-free germplasm for international distribution}, author = {Ng, S. Y. C. and Rossel, H. W. and Thottappilly, G. }, year = {1990}, type = {Integrated pest management for tropical root and tuber crops, edited by S.K. Hahn and F.E. Caveness}, pages = {73--77}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }