1. J. Alexander and A. Hirschowitz, Polynomial interpolation in several variables, J. Algebraic Geom., 4 (1995), 201–222, MR1311347 (96f:14065).
2. A. Białynicki-Birula and A. Schinzel, Extreme binary forms, Acta Arith. 142 (2010), 219–249, MR2606966 (2011d:12001).
3. G. Blekherman, personal correspondence.
4. M. Boij, E. Carlini, A. Geramita, Monomials as sums of powers: the real binary case, Proc. Amer. Math. Soc. 139 (2011), 3039–3043, arXiv:1005.3050, MR2811260 (2012e:11070).
5. M. Brambilla and G. Ottaviani, On the Alexander-Hirschowitz theorem, J. Pure Appl. Algebra, 212 (2008), 1229–1251, arXiv:math/0701409, MR2387598 (2008m:14104).