I found this site awhile back and forgot how to get to it, but now I found it again. I believe it is gendered toward commercial producers for hens at optimal production ,but it seams to be a helpful guide. Providing: a description and a color photographs, the likely incidence in well-managed hens, the possible causes, and possible solutions. Keep in mind though that these are not the average back yard flock. Being that this seems to be more for the commercial aspect some information might to be of value to everyone. In the Aging column the site keeps stating "Keep flock age as low as economically possible." If you are not collecting eggs for product only I would over look this. After a few years hens are not considered to be at optimal production. http://www.thepoultrysite.com 1. Column to the left find Technical Information 2. Follow the pop out to Egg Quality Guide 3. Then of course find what Egg Defect you are looking for Don't Know if this covers all the Egg Defect, But I hope this helps some egg questions.