Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 112.

Jokkmokk, 04/07/1732, ¶560:

“Jumo”-milk; a pint of sorrel is boiled in a little water and stirred until it has boiled to pieces. Then it is mixed with reindeer milk, put into a stomach or some other container and served as needed or eaten at once.