  Considering some important classes of generalized coherent states known in
literature, we demonstrated that all of them can be created via conventional
fashion, i.e. the "lowering operator eigen-state" and the "displacement
operator" techniques using the {\it "nonlinear coherent states"} approach. As a
result we obtained a {\it "unified method"} to construct a large class of
coherent states which already have been introduced by different prescriptions.
