@book{Casper-Hehne:2009,
  author  = "H. Casper-Hehne and A. Middeke and A. Bogner and N. Burneva and M. Freise and E. Nemcová and T. Zuchewicz",
  title     = "Deutsch lernen in Bulgarien: B2/ Nikolina Burneva, Rada Vassileva, Janka Koeva, ISBN: 9789545166464",
  publisher = "Lettera Verlag",
  address   = "Plovdiv",
  pages     = "159",
  year      = "2009",
}