1. Cataract Surgery in Hospital and Practice;Sigmund,1993
2. Department of Health Service, Frederiksborg County. Report on Ophthalmology. Frederiksborg County DK, 1992
3. Department of Health Service, Frederiksborg County. Public Health Care in Frederiksborg County in the Nineties. Frederiksborg County DK, 1992
4. Conversion of keratometer readings to polar values;Naeser;J Cataract Refract Surg,1990
5. Sigmund H. Quality Assurance and Development of Health Service. DSI-Danish Institute for Health Service, Research and Development, 1995; ISBN 87-7488-3119