@inproceedings(nguyen06aiml, 
  author    = {Linh Anh Nguyen},
  title     = {On the Deterministic {Horn} Fragment of Test-free {PDL}},  
  booktitle = {Advances in Modal Logic - Volume 6}, 
  editor    = {I. Hodkinson and Y. Venema}, 
  publisher = {King's College Publications},  
  pages     = {373-392},
  year      = 2006)