1. G K White: Experimental Techniques in Low Temperature Physics (Oxford University Press, 1959)
2. C Kittel: Introduction to Solid State Physics ( Wiley, New York 1953 )
3. A Einstein: Ann. d. Physik 22, 180 (1907)
4. P Debye: Ann. d. Physik 39, 789 (1912)
5. The Salford Analogue and Digital I/O Board, supplied by E & L Instruments Ltd, Rackery Lane, Llay, Wrexham, Clwyd, UK.