FUNCTION {output.nonnull}
{ 's :=
  output.state mid.sentence =
    { ", " * write$ }
    { output.state after.block =
    { ", " *  write$
      newline$
      "newblock " write$
    }
    { output.state before.all =
        'write$
        { ", " *  write$ }
      if$
    }
    if$
      mid.sentence 'output.state :=
    }
  if$
  s
}