booklets:
stabat_mater_bk
  A4, all parts and all instruments and choir, orig. clefs and melismas
stabat_mater_bkc
  choirbook format (190x270mm), just choir voices and parts
stabat_mater_bkd
  choirbook format (190x270mm), all parts and all instruments and choir, but strings in smaller size
stabat_mater_bke
  A4, just choir voices and parts

Only stabat_mater_bkc is worked on for the time beeing,
the others are to be done.