@book{Bortz_2006,
 year = {2006},
 title = {Forschungsmethoden und Evaluation},
 address = {Berlin/Heidelberg},
 publisher = {Springer},
 isbn = {978-3-540-33305-0},
 series = {Springer-Lehrbuch},
 editor = {Bortz, J{\"u}rgen and D{\"o}ring, Nicola}
}