Andrea Sanguinetti sends the following:
Hi, i suggest that in your page of latin chant books you put the following link: http://www.gregofacsimil.net. In that page follow the link ‘RESTITUTIONS’ (in the left part of the page), and you’ll find the whole responsories of officium nocturnum in square notation in pdf files in a transcription according to Hartker manuscript made by D. Crochu & D. Gatté. I think it’s a very important and good work. Regards. Andrea Sanguinetti.
Following the instructions, with my navigation complicated by language and many non-standard characters that do not render properly on my windows laptop, I do find many beautiful PDF files. Perhaps some can explain more about the origin and goal of the project.