bibliography{sources}?

latex makebst

bibliographystyle{custom_style}.

FUNCTION {book}
{ output.bibitem
  author empty$
    { format.editors "author and editor" output.check
      add.colon
    }
    { format.authors output.nonnull
      add.colon
      crossref missing$
        { "author and editor" editor either.or.check }
        'skip$
      if$
    }
  if$
  new.block
  format.btitle "title" output.check
  crossref missing$
    { format.bvolume output
      new.block
      format.number.series output
      new.sentence
      format.publisher.address output
    }
    {
      new.block
      format.book.crossref output.nonnull
    }
  if$
  format.edition output
  format.date "year" output.check
  new.block
  format.url output
  new.block
  format.note output
  fin.entry
}

{ format.authors output.nonnull
      add.colon
      crossref missing$
        { "author and editor" editor either.or.check }
        'skip$
      if$
    }

{
        %format.authors output.nonnull
        %add.colon
        %crossref missing$
            %{ "author and editor" editor either.or.check }
                %'skip$
        %if$
    editor empty$
        {
        format.authors output.nonnull
            add.colon
            crossref missing$
                { "author and editor" editor either.or.check }
                'skip$
            if$
        }
        {
        format.authors format.editors output.nonnull
            add.colon
            crossref missing$
                { "author and editor" editor either.or.check }
                'skip$
            if$
        }

ITERATE {call.type$}

%<<EDITOR IN COLLECTIONS:
%    %: (def) Same as for edited book (names before booktitle)
% edby,%: In booktitle, edited by ..  (where .. is names)
 edby-par,%: In booktitle (edited by ..)
% edby-parc,%: In booktitle, (edited by ..)
% edby,edbyx,%: In booktitle, editor ..
% edby,edbyw,%: In booktitle, (editor) ..
% edby-par,edbyx,%: In booktitle (editor..)
% edby-parc,edbyx,%: In booktitle, (editor..)
% edby,edbyy,%: In booktitle, .., editor
% edby-par,edbyy,%: In booktitle (.., editor)

FUNCTION {incollection}
{ output.bibitem
  format.authors "author" output.check
  add.colon
  new.block
  format.title "title" output.check
  new.block
  crossref missing$
    { format.in.ed.booktitle "booktitle" output.check %<-- this guy it is
      format.bvolume output
      format.number.series output
      format.chapter.pages output
      new.sentence
      format.publisher.address output
      format.edition output
      format.date "year" output.check
    }
    { format.incoll.inproc.crossref output.nonnull
      format.chapter.pages output
    }
  if$
  new.block
  format.url output
  new.block
  format.note output
  fin.entry
}

FUNCTION {format.in.ed.booktitle}
{ format.booktitle duplicate$ empty$ 'skip$
    {
      editor "editor" format.names.ed duplicate$ empty$ 'pop$
        {
          bbl.edby %<-- this one inserts (edited by ...)
          " " * swap$ *
          "(" swap$ * ")" *
          swap$
          " " * swap$
          * }
      if$
      word.in swap$ * %<-- This line adds 'In: ' in front of the booktitle, dont need this in pure books
    }
  if$
}

FUNCTION {format.ed.btitle}
{ format.btitle duplicate$ empty$ 'skip$
    {
        editor "editor" format.names.ed duplicate$ empty$ 'pop$
            {
            bbl.edby
            " " * swap$ *
            "(" swap$ * ")" *
            swap$
            " " * swap$
            * }
        if$
        %word.in swap$ *
    }
    if$
}