Example 3
Tag 07SW, permanent. Cite it as [Bourbaki, Tag 07SW].
Topological Vector Spaces, IV, p. 18, § 2. Bidual. Reflexive spaces
Every strict inductive limit E of a sequence of Montel spaces (II, p. 33) such that is closed in for all n, is a Montel space; in fact, E is Hausdorff (II, p. 32, prop. 9 (i)), barrelled (III, p. 25, cor. 3) and every bounded subset of E is contained in one of the (III, p. 5, prop. 6) hence is relatively compact in , and consequently also in E.
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.