For a period of more than fifty years, Prof. Kaufman has been collecting Jewish musical folklore – songs heard and written down in cities and synagogues, religious and secular, by known and unknown authors. A large volume of these songs exist unaltered, but also a large volume had been arranged by Prof. Kaufman – it is to be published soon. He has researched them as well (there is an article on the subject written by him, in the Bulgarian musicology press), but in his research he does not mention his arrangements.