Cadmus
3 of the 7 encyclopedias on this shelf carry an entry for Cadmus. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
in Greek mythology, the grandson of Poseidon. He was the son of Agenor, king of Phoenicia, and sailed for Greece to seek his sister Europa whom Zeus had carried away. In Greece he met with many adventures. The most noted is that of killing a dragon that guarded the fountain of Ares. At the command of Athene he sowed its teeth in the earth; armed men immediately sprang up and surrounded him, as if to kill him. Athene gave him a jewel to throw among them, whereupon they fell to fighting with each other for its possession. In this way all but five perished. With the survivors, called Spartans, or the sowed, he founded the city of Thebes. To improve the inhabitants of this city, he taught them the Phoenician alphabet. Cadmus means in Semitic speech "the man of the East," while Europa is the damsel who personifies "the West."--Taylor. The foundation of the fable of Cadmus is this: Cadmus having slain a famous free-booter that infested Boeotia, his banditti set upon him to revenge their captain's death; but Cadmus sent a bribe, for which they quarrelled and slew each other.--Brewer.
1000 Classical Characters (1900)
Son of Agenor, king of Phoenicia, and Telephassa, or Agriope, was ordered by his father to go in quest of his sister Europa , whom Jupiter had carried away. His search proving fruitless, he consulted the oracle of Apollo , and was told to build a city where he saw a heifer stop in the grass, and call the country around Boeotia . He found the heifer, as indicated by the oracle. Requiring water, he sent his companions to fetch some from a neighboring grove. The water was guarded by a dragon, who devoured those who were sent for it, and Cadmus, tired of waiting, went himself to the place. He attacked the dragon and killed it, sowing its teeth in the ground, on which a number of armed men rose out of the earth. Cadmus threw a stone among them, and they at once began fighting, and all were killed except five, who assisted him in building the city. Cadmus introduced the use of letters in Greece-the alphabet, as introduced by him, consisting of sixteen letters.
Collier's New Encyclopedia (1921)
according to ancient Greek tradition, the leader of a colony of Phœnicians, who settled at a very early date in Bœotia, and founded the city of Thebes, B. C. about 1450. The Greeks attributed to him the introduction into their country of the 16 simple alphabetical characters; and the close analogy in form between the Greek and Phœnician alphabets renders this account extremely probable. His personal history is almost entirely entirely fabulous.