Analyse Bismarck's alliance system by using historical key concepts (CCCCSP):
A. Dreikaiserbund (The Three Emperor's League, 1873) on pages 18-19
B. The Dual Alliance (1879) on page 27
C. The Three Emperor's Alliance (1881) on page 28
D. The Triple Alliance (1882) on pages 28-29
E. The Reinsurance Treaty (1887) on pages 31-32