@article{10_4007_annals_2012_176_2_6,
     author = {J. William Helton and Scott McCullough},
     title = {Every convex free basic semi-algebraic set has an {LMI} representation},
     journal = {Annals of mathematics},
     pages = {979--1013},
     publisher = {mathdoc},
     volume = {176},
     number = {2},
     year = {2012},
     doi = {10.4007/annals.2012.176.2.6},
     mrnumber = {2950768},
     zbl = {06093945},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4007/annals.2012.176.2.6/}
}