@book{20967,
	author = {Prestel, Alexander and Delzell, Charles N. and Delzell, Charles N. ; jt. auth},
	title = {Positive polynomials; from Hilbert's 17th problem to real algebra},
	publisher = {Springer-Verlag},
	year = {2001},
	series = {Springer monographs in Mathematics},
	address = {Berlin}
}