Corollary 1
Tag 05TU, permanent. Cite it as [Bourbaki, Tag 05TU].
Algebra, chapter II, § 7. Vector spaces
If is a submodule of , is canonically identified with a vector subspace of and with .
It suffices to apply Proposition 27 to the exact sequence
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.