1.c8=Q .Ra1+

2.Na2 Nxc2+

3.Kb3 Bd5+

4.Kxc3 4.Kxc2? Rxa2=Bxa2

5.Kb2 !

(5.Kxc2? Rg1! 6.Qh8+ Kg6=)

(5.Qf5+? Kh6 6.Kb2 Bg8! 7.Qf6+ Kh7=)

5...Bb1

6.Qf5+ Kh4

     (6...Kh6 7.Qg4 Kh7 8.Qg5 Kh8 9.Qg6+_)

7.Qf3!

(7.Kc1? Kg3! (7...Ra4? 8.Kxb1 Nd4  9.Qd7 Rb4+ 10.Ka2+-))

({Try} 7.Qg6? Kh3! 8.Qg5 Ra4 (8...Kh2? 9.Qg4 Kh1 10.Qg3 Ra3 11.Qh4+ Kg1

12.Qg5+ Kf2 13.Qd2+ Kf3 14.Qd1+ Ke4 15.Qxb1+_) 9.Kxb1 Nd4 10.Kb2 Nf3 11.Qf5+ Kg3=)

7...Kg5 (7...Ra4 8.Kxb1 Nd4 9.Qd1+_)

 8.Qe4 {zz} 8...Kf6

9.Qd5 {zz} 9...Ke7

10.Qc6 {zz} 10...Kd8

11.Qb7 {zz} 11...Ke8

12.Qc7 {zz} 12...Kf8

13.Qd7 {zz} 13...Kg8

14.Qe7 {zz}  14...Kh8

15.Qf7 {zz+-} 

correction study  Elerman-120 2014