Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 152.
Jokkmokk [2], 21/07/1732, ¶816:
The sinews best suited to the making of thread are taken from 6 month old reindeer calves, since these make the most pliable thread. The sinews are then covered with tin foil.