text: * Sinyan Shen, Surface Second Sound in Superfluid Helium. PhD Dissertation (1973).  http://adsabs.harvard.edu/abs/1973PhDT.......142S
  * V. Peshkov, "Second Sound in Helium II," J. Phys. (Moscow) 8, 381 (1944)
  * U. Piram, [http://www.inf.ethz.ch/personal/fcellier/MS/piram_ms.pdf "Numerical investigation of second sound in liquid helium,"] Dipl.-Ing. Dissertation (1991).  Retrieved on April 15, 2007.