University of Illinois
University of Illinois Extension: Constructing an Egg Candler
Directions on how to make a device to candle eggs, or check on the progress of the chicken embryo. Links to numerous incubation and embryology resources.
Other
American Egg Board: The Incredible Edible Egg Eggcyclopedia Candling
Brief description of egg candling, one of the tasks of the egg grader. This is part of The Incredible Edible Egg Eggcyclopedia, a searchable dictionary for all things having to do with eggs.