S.-J. Hwang, C. Fernandez, J.P. Amoureux, J. Cho, S.W. Martin, M. Pruski, (1997). Quantitative study of the short range order in B2O3 and B2S3 by MAS and two-dimensional triple-quantum MAS B NMR. Solid State Nuclear Magnetic Resonance 8 (2): 109–121. doi: 10.1016/S0926-2040(96)01280-5. PMID 9203284.