Originally posted by heinzkat1. Nxf6+ gxf6 2. Rhg1+ Kh8 3. Nxf7+ Rxf7 4. Rd8+ and mate follows soon.
Oh the previous position (1. Re8+ Be7 2. Nd5! and mate in a few) was from Ushenina - Velcheva, 2006. 2. Bd8 wins just as convincing.
[fen]rn3rk1/5ppp/p1bNpb2/4p3/4N3/1B3P2/PPP2P1P/2KR3R w - -[/fen]
White to move.
Originally posted by heinzkat1. Qd8+ Rxd8 2. Ne7+ Bxe7 3. Nb6#
I had seen it before - I even could retrieve the composer's name, but now I see you had already verified the solution and given the author's name (editing for nothing).
[fen]Nqk1r2r/1p1n2p1/bQNbBn1p/5P2/5B2/1P4P1/5PK1/8 w - -[/fen]
White to move