The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
bhgo-
DEFINITION:
Beech tree. 1a.book, from Old English bc, written document, composition; b.buckwheat, from Middle Dutch boek, beech; c.Bokmål, from Norwegian bok, book. ac all from Germanic *bk, beech, also beech staff for carving runes on (an early Germanic writing device). 2.beech, from Old English bce, beech, from Germanic *bkjn-. (Pokorny bhgó-s 107.)