The 'introduction' mentions Hans Walter Gabler’s book 'Critical and Synoptic Edition' (in 3 volumes) that compares all the different editions and notes all the

The 'introduction' mentions Hans Walter Gabler’s book 'Critical and Synoptic Edition' (in 3 volumes) that compares all the different editions and notes all the (often small) differences. I feel it typically a book that would be much more worth in digital form. (It would be nice if the author would allow it to be digitized.) If one would have the digital form of all the editions, it would be much easier to compare them. I am aware that this will be an enormous effort.