I have found the "Handbook" to be most useful. I disagree with my Swedish friend above about the book. In fact below is a snippet from THE journal of leadership about the book. According Schriesheim, Scandura, Gardiner and Lankau (1993) the Handbook is "the outstanding foundation source for information on leadership theory and research" (p. 104). Schriesheim et al. state further that the handbook is "the source which scholars should consult first in attempting to understand any of the subsidiary topics...subsumed under the general rubric of 'leadership theory and research'" (p. 108).
Reference: Schriesheim, C. A., Scandura, T. A., Gardiner, C. C., & Lankau, M. J. (1993). Book Review: Bass & Stogdill's handbook of leadership: Theory, research & managerial applications by Bernard Bass. Leadership Quarterly 4(1), 103-113.