1. Teledyne Benthos web site, http://www.benthos.com
2. Hamamatsu web site, http://www.hamamatsu.com
3. Wacker Chemie AG, http://www.wacker.com/cms/en/home/index.jsp
4. Institute for Theoretical and Experimental Physics, Moscow, http://www.itep.ru
5. SEG web site, http://www.iseg-hv.com