1. Permanent address: Mechanical Engineering Department, 41–206, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge MA 02139.
2. A. Watanabe, G. W. Swift, and J. G. Brisson, Measurements with a recuperative superfluid Stirling refrigerator (1996) elsewhere in this volume; and references therein.
3. G. Walker, “Stirling Engines,” Clarendon, Oxford (1960).
4. G. Walker, “Cryocoolers,” Plenum, New York (1983).
5. R. Radebaugh, Advances in Cryogenic Engineering 35:1191 (1990).