ROBERTS, E. Poor pitch singing: Response monotone singers to a program of remedial training. J. Research in Music Education. 1975, 23, 227-237
PORTER, Y. The effects of multiple discrimination training on pitch matching behavior uncertain singers. J. Research in Music Education. 1977, 25, 68-81
GERINGER, J. The relationship of pitch matching and pitch discrimination abilities of preschool and forth-grade students. J. Research in Music Education. 1983, 31, 93-139