Where's Gade? (In most measures of this piece, that's where!) William Wieland
But wait, there's a little more! The first 3 chords and the first 3 chords after the repeat sign are Gm - A - Dm. The chords in bars 5 & 17 are G - A - Dm.
The motive derived from Gade provides great unity. Schumann transforms this motive to give us great variety.