Key points are not available for this paper at this time.
Robert A. Connolly, Barry T. Hirsch, Mark Hirschey, Union Rent Seeking, Intangible Capital, and Market Value of the Firm, The Review of Economics and Statistics, Vol. 68, No. 4 (Nov., 1986), pp. 567-577
Connolly et al. (Sat,) studied this question.