Kiertichai J. Amphywong และ Jumpol Prompitak. (1976) On reduction of positive feedback by audio frequency processing techniques. Chulalongkorn University:ม.ป.ท.Kiertichai J. Amphywong และ Jumpol Prompitak. 1976. On reduction of positive feedback by audio frequency processing techniques. ม.ป.ท.:Chulalongkorn University;Kiertichai J. Amphywong และ Jumpol Prompitak. On reduction of positive feedback by audio frequency processing techniques. ม.ป.ท.:Chulalongkorn University, 1976. Print.