Attached find some files, on this method.

If you search some books are also available.

Dear,

Try this references and you can find some books contain the basic concepts of HAM written by Liao :

Liao, S. (2003).Beyond perturbation: introduction to the homotopy analysis method. CRC press, Boca Raton, Chapman and Hall. Liao, S. (2004).

On the homotopy analysis method for nonlinear problems, Appl Math Comput., 147, 499-513. Liao, S. (2005).

Comparison between the homotopy analysis method and homotopy perturbation method. Appl Math Comput, 169, 1186-94.