Calculated tautomeric equilibria and X-ray structures of 2-substituted N-methoxy-9-methyl-9H-purin-6-aminesGundersen, Lise-Lotte; Görbitz, Carl Henrik; Neier, Liina; Roggen, Heidi; Tamm, ToomasTheoretical chemistry accounts2011 / p. 349-359 Structure and stability of gold-substituted diborane, boranes, and borohydride ionsTamm, Toomas; Pyykkö, PekkaTheoretical chemistry accounts2000 / p. 399-408 https://link.springer.com/article/10.1007/s002149900063