Reaction Mechanism In Organic Chemistry By Mukherjee And Singh Here

Exceptionally detailed, step-by-step arrow-pushing mechanisms for mixed competitive reactions (e.g., substitution vs. elimination).

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It sounds like you're looking for a (or a distinctive characteristic) of the book Reaction Mechanism In Organic Chemistry by S.M. Mukherjee and S.P. Singh (often published by Macmillan or similar).