I don't have a good system yet for bibliography. What I'm doing is, once I finish a chapter, collating its bibliography into a master bibliography for the whole book. When I do this collation, I eliminate duplicate entries. Then, when the book is complete, I have to make sure each reference in each chapter is in the master list, that all references are unambiguous, etc... For example, I cannot say "Mayhew 12" when there are seven work by Mayhew in the bibliography. Page 12 of what work by Mayhew?
Problems come when I revise a chapter, and have to keep the bibliography up to date; when I eliminate a chapter and have to expunge references in the bibliography. Also, the longer the master bibliography, the harder it is to collate with a list of new entries. Maybe I should keep copies of individual bibliographies, for each chapter, for my own reference, rather than folding them into the cake batter?