There are at least 2 excellent books where the Lebensohl theme is thoroughly examined and described: 1. Parthership Bidding at bridge- by Andrew Robson and OliverSeagal 2. Better bidding with Bergen part II - by Marty Bergen One good practical advice from there: If both opponents have bid without our intervention we assume they've shown min 18-19 p combined strength (and our game already is not so probable) and 2NT should be "Scrambling"=2 or 3 places to play for ex: 1S-p-2S-DBL p - ? here 2NT is scrambling 4-4 in 2 suits ouside S, or 4S333 (with H suit still may distinguish good bid via direct 3H and bad bid through slow 2NT-any-3H, keeping the chances for evaluation of our H game) On the contrary if 2nd opponent bids after our action, especially when fitting his Partner then opponets might show weaker combined strentgh based on good fit only (and our game remains enough probable) and there 2NT should be Lebensohl oriented for ex: 1S-DBL-2S - ? here 2NT=Lebensohl willing to compete only(5-7 points 5 card suit, while direct bid on level 3 is full balance (8-11 points)
