Before Benko

In Steiner's book "Kings of the Chess Board" he annotates Szabo v Lundin from the 1948 Saltsjobadan Interzonal. What is interesting about this game is that it is a Benko Gambit, before there was the Benko Gambit. In his notes Steiner refers to it as a "Blumenfeld Gambit" although he does note that the Blumenfeld Gambit starts with 1.d4 Nf6 2.c4 c5 3.d5 e6 4.Nc3 b5. Now while Benko's chess career had started by this stage (and Steiner discusses him in the book) I haven't been able to find any games by Benko that use the "Benko" before this. Of course the variation is also known as the "Volga Gambit" but I have been told that to use this name within earshot of Pal Benko is asking for a ticking off.

Szabo,L - Lundin,E [A58]
Saltsjobaden Interzonal Saltsjobaden (19), 1948

1.d4 Nf6 2.c4 c5 3.d5 b5 (D)
4.cxb5 a6 5.bxa6 g6 6.Nc3 Bxa6 7.e4 d6 8.Bxa6 Nxa6 9.Nf3 Bg7 10.0-0 Nd7 11.Bf4 0-0 12.Qe2 Qc7 13.Rfc1 Rfb8 14.Rab1 Bxc3 15.Rxc3 Qa5 16.Nd2 Nc7 17.Ra3 Qb6 18.Rxa8 Rxa8 19.a3 Nb5 20.Be3 Ra4 21.Rc1 Nd4 22.Bxd4 cxd4 23.Nf3 Nf6 24.Qc2 Ra5 25.Nd2 d3 26.Qc7 Qxb2 27.e5 Qxd2 28.exf6 exf6 29.h4 Kg7 30.Qc3 Qxc3 31.Rxc3 Rxd5 32.Rc1 g5 33.Kf1 gxh4 34.Ra1 f5 35.a4 Kf6 36.Ke1 Re5+ 37.Kd2 Re2+ 38.Kxd3 Rxf2 39.a5 Rxg2 40.a6 Rg8 41.Kc4 f4 42.Kd5 Kf5 43.Kc6 f3 44.Kb7 0-1