RISCHEL, J.; LYSTLUND, S.-E. The Heterodyne Filter of the Institute of Phonetics. Annual Report of the Institute of Phonetics University of Copenhagen, [S. l.], v. 2, p. 20–34, 1968. DOI: 10.7146/aripuc.v2i.130673. Disponível em: https://tidsskrift.dk/ARIPUC/article/view/130673. Acesso em: 9 may. 2024.