A Six-Coloring of the Plane. - Alexander Soifer (J. Comb. Theory A, 1992)

Another six-coloring of the plane. - Ilya Hoffman; Alexander Soifer (Discret. Math., 1996)

Axiom of choice and chromatic number of the plane. - Saharon Shelah; Alexander Soifer (J. Comb. Theory A, 2003)

Axiom of choice and chromatic number: examples on the plane. - Alexander Soifer; Saharon Shelah (J. Comb. Theory A, 2004)

Axiom of choice and chromatic number of Rn. - Alexander Soifer (J. Comb. Theory A, 2005)

Covering a square of side n+epsilon with unit squares. - Alexander Soifer (J. Comb. Theory A, 2006)

The Hadwiger-Nelson Problem. - Alexander Soifer (Open Problems in Mathematics, 2016)