# Diagonalisation of the g-matrix of low symmetry transition ions.
# [httphttps://www.academia.edu/attachments1267029/7689768/download_file The_Use_of_Irreducible_Operators_for_Determining_the_Complete_Set_of_Linearly_Independent_Crystal_Field_Parameters The Use of Irreducible Operators for Determining the Complete Set of Linearly Independent Crystal Field Parameters].
# The main equations which define an effective Hamiltonian.
# [http://cyt-ar.com.ar/cyt-ar/images/9/95/General_Theory_of_Effective_Hamiltonians.pdf General theory of Effective Hamiltonians].