Yak
2 of the 7 encyclopedias on this shelf carry an entry for Yak. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
the native name for the Poephagus grunniens, a species of ox from the mountainous regions of Tibet. There are two races: the wild yak, generally black, which is found near the snow line, descending into the valleys in winter, and a domesticated race of various colors, black and white being most common. The yak is about the size of the common ox to which it has a general resemblance, but it is covered with a thick coat of long, silky hair, hanging down like the fleece of a sheep, completely investing the tail, and forming a lengthy fringe along the shoulders, flanks, and thighs. This fringe, which exists in both races, was apparently developed as a protection to the animal in its alpine haunts, as the long hair forms a sort of mat which defends the body from the effects of the cold when the animal is reposing in the snow. The domesticated race is of great importance to the natives of Tibet. The yak is employed as a beast of burden, but never for tillage or draught; the milk is very rich, and yields excellent butter; the flesh is of the finest quality, and that of the calves far superior to ordinary veal. The hair is spun into ropes, and made into coverings for tents, and the soft fur of the hump and withers is woven into a fine strong cloth. The tails, often dyed red, are made into the chowries or fly-flappers, used in India. Yaks are often seen in zoölogical gardens and menageries, and have repeatedly bred in Europe, and it is probable that they might be advantageously introduced into the Highlands of Scotland and the N. parts of the Continents of America and Europe.
Aiton's Encyclopedia (1910)
yak, the black wild ox of Thibet, sometimes called the grunting ox. The yak is native in the high altitudes of Central Asia. Nature has draped this animal with long hair reaching from the sides almost to the ground, resembling in this respect its relative, the musk ox of Arctic latitudes. Naturalists have not failed to point out that cold weather, due to altitude, has done for the yak what similar conditions, due to latitude, have done for the musk ox. The yak is about four feet high. It carries a pair of fine ox-like horns. It has long been domesticated by the Thibetans among whom it is the principal beast of burden. The yak furnishes excellent beef, milk, and butter, also. Its long, silky hair is woven into clothing. Its back is slightly humped, like the American bison. The yak's tail was an emblem of authority among the Orientals. The yak is stubborn, but it is more serviceable than the horse or camel for snowy, mountain work. In conducting military operation in that region, the British have found it convenient to employ the yak not only in packing baggage, but as a riding animal. See Camel ; Reindeer