1. J. Billingsley and R. Kinns, J. Sound Vib. 48, 485 (1976).
2. U. Michel, in Proc. 1st Beamforming Conf. (Berlin, 2006).
3. T. Padois, O. Robin, and A. Berry, in Proc. 19th AIAA/CEAS Aeroacoustics Conf. (Berlin, 2013), Paper 2013-2213.
4. E. Sarradj, Adv. Acoust. Vib., No. 4, 292695 (2012).
5. R. Porteous, Z. Prime, C. Doolan, D. Moreau, and V. Valeau, J. Sound Vib. 355, 117 (2015).