Return of the Master

(1) Aagaard,Jacob (2420) - Kempinski,Robert (2545) [E61]
Groningen op Groningen (10), 30.12.1998
[Reeh,Oliver]

1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.Nf3 0-0 5.Bf4 d6 6.h3 Qe8 7.e3 Na6 8.Be2 Nh5 9.Bh2 f5 10.Rb1 f4 11.b4 c5 12.b5 Nc7 13.0-0 b6 14.Nd5 Nxd5 15.cxd5 fxe3 16.fxe3 Bh6 17.Qd3 Bf5 18.e4 Bd7 19.Qb3 Nf4 20.Bc4 Qc8 21.e5 cxd4 22.e6 Be8 23.g3 Nh5 24.Kh1 Qc5 25.g4 Rc8 26.Bd3 Nf4 27.g5 Bg7 28.Bxf4 Rxf4 29.Nd2 Rh4 30.Rf3 h6 31.Ne4 Qc7 32.gxh6 Rxh6 33.Rg1 Qb7 34.Rfg3 Rh5 35.Rg5 Rxh3+ 36.Kg2 Re3 37.Rg3 Rxg3+ 38.Kxg3 Bh6 39.Rh1 Kg7 40.Bc4 Be3 41.Qb2 g5 42.Kg4 Bd7 43.Nxg5 Rxc4 44.Rh7+ Kg6 45.Rh6+ Kg7 46.Rh7+ Kg6 47.Rh6+ Kg7 48.Qg2 Bxg5 49.Kxg5 Be8

 50.Kf5+? White decides to go for the perpetual and the game is drawn  after 50...Kxh6 51.Qg5+ Kh7 52.Qh4+ Kg7 1/2-1/2

how (white to play in the above postion) could have won?

source :chess base