A few difficulties in Besterman's bibliography concern what have been called "linked" books. These are works having their own title pages but issued in conjunction with another book.[200] Unless they have been catalogued as separate works, they are virtually impossible to identify. We have already seen what annoyance a title of this sort can cause in the case of Labbé's bibliography of bibliographies published in 1653. I cannot reach a decision altogether satisfactory to myself regarding Besterman's inclusion of "abridgments of patent specifications" (I, p. xv). These contain bibliographical information not readily obtainable from any other source, and my disposition is inclined toward generosity. By including them Besterman offers a much more adequate representation of scientific and technological bibliography than would otherwise have been possible. As he correctly says (I, p. xvii), an interest in the fields of humane studies has been predominant in earlier bibliographies of bibliographies. On the other hand, Besterman seems, in including these abridgments, to have stretched to the breaking point his rule for the exclusion of bibliographies contained in non-bibliographical works. If these abridgments are to be included, then one is tempted to call attention to the fact that many German doctoral dissertations offer good bibliographies of small subjects and can be very useful on occasion.[201] Any definition of a bibliography is difficult to formulate and even more difficult to adhere to. I cite only one more illustration of the problems that arise. Besterman cites (col. 1040) Antti Aarne's catalogue of printed and manuscript versions of Finnish tales. This is clearly within his definition of a bibliography. Perhaps a score of similar catalogues for the tales of countries from Iceland to Rumania are in existence and might equally well have been cited. Although it is not made according to Aarne's pattern, the _Typen türkischer Volksmärchen_ (Wiesbaden, 1953) by Wolfram Eberhard and P. N. Boratav is a similar catalogue of tales. How far shall one go in seeking out such extremely technical reference aids as these? The specialist will know them, and few others can use them with any comfort. Students of folklore have done a great deal of indexing and cataloguing and have produced works that can only be separated from bibliographies with difficulty. What shall one say of John Meier, _Kunstlieder im Volksmunde_ (Halle, 1906)? This is a catalogue of German songs that have been heard in oral tradition but can be traced back to known authors. Meier gives full references to the sources in both the printed works of the authors and the collections of folksongs. To return to tales once more, I mention two books of an apparently wholly bibliographical nature that Besterman does not mention. A. C. Lee, _The Decameron. Its Sources and Analogues_ (London, 1909) is, as its title indicates, a compilation of tales related to those in the _Decameron_.