1. R. P. Feynman , in Progress in Low Temperature Physics , ed. C. J. Gorter , North-Holland , Amsterdam , 1955 , vol. 1, p. 1
2. R. J. Donnelly , Quantized Vortices in Helium II , Cambridge University Press , Cambridge, England , 1991
3. Visualization of quantized vortices
4. Characterization of reconnecting vortices in superfluid helium
5. Visualization of Superfluid Helium Flow