I'm studying a perturbation theory (behaviour of its series) and have found two articles which might be of particular interest. Unfortunately, all my three institutions do not have subscription to these journals (articles are too old). I'm kindly asking for your help. These are the articles I'm looking for: 1. http://jcp.aip.org/resource/1/jcpsa6/v49/i7/p3035_s1 [Broken], doi:10.1063/1.1670546 2. http://iopscience.iop.org/0370-1328/78/4/306, doi: 10.1088/0370-1328/78/4/306 Thank you very much in advance. I would also appreciate any review articles on the problem of convergence of perturbation series in an "old" theory and a diagrammatic one.