1. J. Berndt, F. Tricerri, L. Vanhecke, Generalized Heisenberg groups and Damek–Ricci harmonic spaces. Springer 1995. MR1340192 Zbl 0818.53067
2. G. Cairns, A. Hinić Galić, Y. Nikolayevsky, Totally geodesic subalgebras of nilpotent Lie algebras. J. Lie Theory23 (2013), 1023–1049. MR3185210 Zbl 06255249
3. P. J. Cameron, Minimal edge-colourings of complete graphs. J. London Math. Soc. (2) 11 (1975), 337–346. MR0422088 Zbl 0312.05107
4. P. J. Cameron, Resolutions of the pair design, or 1-factorisations of complete graphs. Accessed September 13 2015, http://designtheory.org/library/encyc/topics/onefact.pdf
5. G. Crandall, J. Dodziuk, Integral structures on H-type Lie algebras. J. Lie Theory12 (2002), 69–79. MR1885037 Zbl 1035.17018