Board R G, Perrott H R
Calcif Tissue Int. 1979 Nov;29(1):63-9. doi: 10.1007/BF02408056.
The crystalline spherules occurring in patches on the outer surface of the eggshells of Guira guira and the bloom on the entire outer surface of those of Crotophagi ani were shown by X-ray diffraction analysis to be vaterite.