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@article{PORMA_1961__20_2_114854, author = {Shapiro, H.S.}, title = {On a class of extremal problems for polynomials in the unit circle}, journal = {Portugaliae mathematica}, pages = {67--93}, publisher = {mathdoc}, volume = {20}, number = {2}, year = {1961}, mrnumber = {0130973}, zbl = {0097.28001}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1961__20_2_114854/} }
Shapiro, H.S. On a class of extremal problems for polynomials in the unit circle. Portugaliae mathematica, Tome 20 (1961) no. 2, pp. 67-93. http://geodesic.mathdoc.fr/item/PORMA_1961__20_2_114854/