13C NMR SPECTRA OF METHYL- AND NITRO-SUBSTITUTED AZAFLUORENES ArticleGolovtsov N.I., Fomichev A.A., Pleshakov V.G., Zvolinskii V.P., Zakharov V.Z., Prostakov N.S.Theoretical and Experimental Chemistry. Vol. 18. 1983. P.. 336-338