Waring's problem for polynomial cubes and squares over a finite field with odd characteristic. Gallardo, Luis (2004) Portugaliae Mathematica. Nova Série
What is the value of Taxicab ( 6 ) ? Calude, Cristian S., Calude, Elena, Dinneen, Michael J. (2003) Analele Ştiinţifice ale Universităţii “Ovidius" Constanţa. Seria: Matematică