singh s n, katyal M & agarwal r k. (1990). Molecular structure a spectroscopic approach. new delhi: Discovery Publishing House.
singh s n, katyal M and agarwal r k. 1990. Molecular structure a spectroscopic approach. new delhi: Discovery Publishing House.
singh s n, katyal M and agarwal r k. (1990). Molecular structure a spectroscopic approach. new delhi: Discovery Publishing House.
singh s n, katyal M and agarwal r k. Molecular structure a spectroscopic approach. new delhi: Discovery Publishing House. 1990.