It¿'s Lemma: Lemma, Mathematics, It¿ Calculus, Differential (calculus)

Fundamental Lemma of Calculus Variations: Mathematics, Variations, (mathematics)

Morse Palais Lemma: Mathematics, Calculus of Variations, Hilbert Spaces

Bihari's Inequality: Grönwall's Lemma, Mathematics, Differential Inequality

Stewart Walker Lemma: Metric (Mathematics), Pullback (Differential Geometry)