I need the following articles but I don't seem to have access to them. Would appreciate if anybody can help.
http://iopscience.iop.org/0022-3727/38/2/011
http://www.sciencedirect.com/science/article/pii/S1359645405004404

Hi, I can't get the Journal of Physics one but I do have access to the ScienceDirect one - if you PM me your email address I can send it over.

Hi Igorina, I have sent you my email address. Thanks a lot for your help.