@article{SchulerMusekampBengeletal.2014,
  author    = {Michael Schuler and Gunda Musekamp and J{\"u}rgen Bengel and Sandra Nolte and Richard H. Osborne and Hermann Faller},
  title     = {Measurement invariance across chronic conditions: a systematic review and an empirical investigation of the Health Education Impact Questionnaire (heiQ™)},
  doi       = {10.1186/1477-7525-12-56},
  year      = {2014},
}