The  book  in  hand  consists of four reprints, each with its  own (facsimile of)  the  original title page.  There is also  a collective t.p. naming all  four included titles and their authors. What is  the chief source of information for the  NAR?
 
The chief source for the  NAR  is  the chief source  for  the piece in  hand (cf. rule 22.1B which refers to  1.0A  on  chief sources).  Information from  elsewhere  in  the  piece  can  provide additions to  the heading (dates or spelled-out forms  of
initials, for example), but  the heading itself  comes  from  the  chief source.
Note  that the question refers  to  "the  NAR" rather  than  "the  NARs" because it does not come under  rule  21.7   on
"collections of  works  by  different persons  or  bodies."   As the piece has  more  than  three responsible persons  or  bodies, one should follow either rule 21.7B1 (at  the  end) or rule 21.7C1, depending on whether or  not the item has  a   collective title as well as a collective t.p., and trace only the   *first* person or body named in the chief source.