Nonplanarity at tri-coordinated aluminum and gallium: cyclic structures for X3Hn(m) (X = B, Al, Ga).
Srinivas GN, Anoop A, Jemmis ED, Hamilton TP, Lammertsma K, Leszczynski J, Schaefer HF. Nonplanarity at tri-coordinated aluminum and gallium: cyclic structures for X3Hn(m) (X = B, Al, Ga). J Am Chem Soc. 2003 Dec 31; 125(52):16397-407.