Hilbert-Waring Theorem/Variant Form/Particular Cases/2

Particular Case of the Hilbert-Waring Theorem -- Variant Form: $k = 2$
The Hilbert-Waring Theorem -- Variant Form states that:

The case where $k = 2$ is proved by Lagrange's Four Square Theorem‎:
 * $G \left({2}\right) = 4$

That is, every sufficiently large positive integer can be expressed as the sum of at most $4$ squares.