T. Le-Tien, H. Tran-Thanh, D. Tran-Tien, and C. Hoang-Dinh, “RECOGNIZING FORMANTS AND PITCH PERIODS FOR VIETNAMESE SPEECH BASED ON THE LOCAL MODULUS MAXIMA IN THE WAVELET DOMAIN”, Science and Technology Development Journal, vol. 4, no. 1&2, pp. 43-55, Feb. 2001.