"Scaling and instability of a junction vortex" J. J. Allen and Takashi Naitoh, J. Fluid Mech. 574, 1-23 (2007)
"Experimental study of the production of vortex rings using a varialbe diameter orifice" J. J. Allen and Takashi Naitoh, Phys. Fluids Letter 17, 061701 (2005)
"Experimental study of axial flow in a vortex ring" Takashi Naitoh, Naohiko Fukuda, Toshiyuki Gotoh, Hideo Yamada, and Kei Nakajima, Phys. Fluids 14(1), 143 (2002)