Frese, M., Fay, D., Hilburger, T., Leng, K., & Tag, A. (1997).
The concept of personal initiative: Operationalization, reliability, and validity in two German samples.
Journal of Occupational and Organizational Psychology, 70, 139–161.
.
Personal initiative at work: Differences between East and West Germany.
Frese, Michael Kring, Wolfgang Soose, Andrea Zempel, Jeannette ;
Academy of Management Journal, Vol 39(1), Feb, 1996. pp. 37-63