1. Anon 2010 Animal Farm Life: Tracing the Lives of Farm Animals www.animalfarmlife.eu/index.html
2. Sequential studies of skeletal calcium reserves and structural bone volume in a commercial layer flock;Cransberg;British Poultry Science,2001
3. Defra 2011 Eggs www.defra.gov.uk/statistics/foodfarm/food/eggs
4. The pros and cons of cages;Duncan;World's Poultry Science Journal,2001
5. Council Directive 1999/74/EC of 19 July 1999 laying down minimum standards for the protection of laying hens;European Commission;Official Journal L,1999