Lagrange's four-square theorem - Wikipedia

Chit-chat on Lagrange's four-square theorem

PDF) Two refinements of Lagrange's four-square theorem

Table 3 from Extended Lagrange's four-square theorem

Lagrange's Four-Square Theorem -- from Wolfram MathWorld

Lagrange's four-square theorem

GitHub - HechenHu/Four-Square_Representation: Using Rabin and Shallit's Algorithm to compute the four-square representation of a natural number as stated in Lagrange's Four-square Theorem.

Lagrange's 4 Square Theorem using Python

PDF) Sums of four squares and Waring's Problem

Lagrange and the four-square theorem - Archive ouverte HAL

Sum of Squares Function -- from Wolfram MathWorld