Lagrange's four-square theorem - Wikiwand

Chit-chat on Lagrange's four-square theorem

Table 1 from Extended Lagrange's four-square theorem

Solved In Number Theory, Lagrange's four-square theorem

PDF) A Simple Proof of Jacobi's Four-Square Theorem

Square Number Definition & Meaning

Lagrange's Four-Square Theorem Seen Using Polygons and Lines

CodeChef - Lagrange's four-square theorem, also known as Bachet's conjecture, states that every natural number can be represented as the sum of four integer squares. This theorem was proven by Joseph Louis

Lagrange's Four-Square Theorem by Julian TSE

Sum of two squares theorem - Wikipedia

Euler Four-Square Identity -- from Wolfram MathWorld