1. Allen C.W., Astrophysical quantities, 1964, The Athlone Press, London.
2. Analog Devices,Data Acquisition Products Catalogue, Route One , Industrial Park,Norwood HA 02026, USA.
3. De Biase G.A., Sedmak G., Astron.A strophys. 33, 1974, 1.
4. De Biase G.A.,Paternò L.,Pucillo N.,Sedmak G.,Appl. Opt. 17, 1978, 435.
5. DEC Computer Systems Data Catalogue, Digital Equipment Corporation, 146 Nain Street, Maynard MA 01754, USA.