@book{31597,
	author = {Spangenberg, Karl R.},
	title = {Vacuum tubes /},
	publisher = {McGraw-Hill Book,},
	year = {c 1948.},
	series = {McGraw-Hill electrical and electronic engineering series},
	address = {New York :},
	edition = {1st ed.},
	note = {Includes index.}
}