@article{cable1975the, title = {The Qualification of Loudspeaker Directivity Factor in Sound Reinforcement System Design}, author = {Cable, Cecil R.}, journal = {J. Audio Eng. Soc}, volume = {23}, number = {6}, pages = {434--441}, year = {1975}, url = {https://www.aes.org/e-lib/browse.cfm?elib=2684} }