@article{heyser1969loudspeaker, title = {Loudspeaker Phase Characteristics and Time Delay Distortion: Part 1}, author = {Heyser, Richard C.}, journal = {J. Audio Eng. Soc}, volume = {17}, number = {1}, pages = {30--41}, year = {1969}, url = {https://www.aes.org/e-lib/browse.cfm?elib=1608} }