Alcock, Joan Pilsbury (2006). Food in the Ancient World. Greenwood Publishing Group. стр. 83. ISBN9780313330032. „Curdled milk (oxygala or melca), probably a kind of yogurt, was acceptable because it was easier to digest. Even so, it was still to be mixed with honey or olive oil. Columella gave instructions on how to make sour milk with seasoning into ...”
Hoffman, Susanna (2004). The Olive and the Caper: Adventures in Greek Cooking. Workman Publishing. стр. 471. ISBN9780761164548. „...something like yogurt was known to Greeks since classical times – a sort of thickened sour milk called Pyriate or oxygala. Oxi meant "sour" or "vinegar"; gala, "milk". Galen says that Oxygala was eaten alone with honey, just as thick Greek yogurt is today.”
Tribby D (2009). „Yogurt”. Ур.: Clark C, et al. The Sensory Evaluation of Dairy Products. Springer Science & Business Media. стр. 191. ISBN9780387774084.
The Natural History of Pliny, tr. John Bostock, Henry Thomas Riley, London: Bell, 1856–93, Volume 3, p. 84: "It is a remarkable circumstance, that the barbarous nations which subsist on milk have been for so many ages either ignorant of the merits of cheese, or else have totally disregarded it; and yet they understand how to thicken milk and form therefrom an acrid kind of milk with a pleasant flavor".