Cardiff University has an index online, the Cardiff Index To Legal Abbreviations. It apparently contains over 6,600 titles and 11,700 abbreviations drawn from over 180 jurisdictions. It also appears to work with inexact matches, which is good, because the abbreviations encountered in texts aren’t always standard.
You can search for NJW or Neue Juristische Wochenschrift, that is, on the abbreviation or on the title.
bq. The database mainly covers law reports and law periodicals, but some legislative publications and major textbooks are also included. The Index is still under development.
About the index. This is what they consulted on Germany:
bq. Basic Literature on Law. Ralph Lansky. C.H.Beck, 2nd edition, 1978.
bq. Charles Szladits Guide to Foreign Legal Materials: German. Timothy Kearley and Wolfram Fischer. Oceana Publications Inc., for the Parker School of Foreign and Comparative Law, Columbia University, New York, 2nd revised edition, 1990.
That makes it a bit out of date, to say the least. I did a search for Ralph Lansky. I have the impression that the ‘title’ is purely a translation for catalogue purposes. So law librarians list books under titles they were not published under. Anyway, Ralph Lansky, born in Riga in 1931, is a former director of the library of the Max Planck Institute.