@article{10_26493_1855_3974_518_768,
     author = {Kristijan Cafuta and Igor Klep and Janez Povh},
     title = {
		{Rational} sums of hermitian squares of free noncommutative polynomials
	},
     journal = {Ars mathematica contemporanea},
     pages = {243--259},
     year = {2015},
     volume = {9},
     number = {2},
     doi = {10.26493/1855-3974.518.768},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.26493/1855-3974.518.768/}
}