One considers representation of cubic polynomials in several variables as the sum of values of univariate polynomials taken at linear combinations of the variables.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm92-1-6,
author = {A. Schinzel},
title = {On a decomposition of polynomials in several variables, II},
journal = {Colloquium Mathematicae},
volume = {91},
year = {2002},
pages = {67-79},
zbl = {0987.12001},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm92-1-6}
}
A. Schinzel. On a decomposition of polynomials in several variables, II. Colloquium Mathematicae, Tome 91 (2002) pp. 67-79. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm92-1-6/