Bronznik (in "1.d4 - Ratgeber gegen Unorthodoxe Verteidigungen", Kania 2010, p. 53) writes:
Quote:Leider verfügt Schwarz nach [1.d4 e6 2.c4] Lb4 3.Sc3 über mindestens drei andere recht gute Fortsetzungen: 3...c5!?, 3...f5!?, 3...b6!?, und jede von ihnen verspricht ein zufriedenstellendes Spiel.
My translation: "Unfortunately [from White's point of view - Zzz], after 1.d4 e6 2.c4 Bb4 3.Nc3 has at least three other reasonable moves [apart from 3...Nf6 - Zzz]: 3...c5!?, 3...f5!?, and 3...b6!?, and each one of them promises a satisfying position."
Bronznik clearly recommends 3.Bd2.
If you look at the statistics, after all three moves White scores between 47 % (after 3...c5) and 49 % (after 3...f5), the statistics seem to be based on a reasonable amount of games, and the TPR seems to indicate that White players have approximately the same strength as Black players. So 3.Nc3 should be a minor concern. In my database, there are 13 games from Eingorn (after 3.Nc3 c5), covering 4.a3, 4.e3, 4.d5 and 4.Nf3, scoring 9.5 points. As there might be no coverage anywhere else, I'd recommend to beginn with studying those games!?
In CI, there are at least three reasonably annotated games: Gurevich-Hansen, Taastrup 1992 (CI 54), Flear Dorfman, Polanica Zdroj 1992 (CI 55), and Ivanov-Hillarp Persson, Stockholm 2001 (CI 83), so they might also be of some help.
Best regards,
Zwischenzugzwang