To be fair for textbooks at least I often see several results but often of different editions (1x edition 1, 2x edition 2, 1x edition 3 etc.). In some cases I t

To be fair for textbooks at least I often see several results but often of different editions (1x edition 1, 2x edition 2, 1x edition 3 etc.). In some cases I think it's worthwhile keeping the different additions around, unless it becomes a huge burden.