Paper  bibtex   

@article{ choi_observer-based_1998,
  title = {An observer-based controller design method for improving air/fuel characteristics of spark ignition engines},
  volume = {6},
  url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=668034},
  number = {3},
  urldate = {2013-09-24},
  journal = {Control Systems Technology, {IEEE} Transactions on},
  author = {Choi, Seibum B. and Hedrick, J. Karl},
  year = {1998},
  pages = {325–334}
}