I got 8 reference letters from 5 countries.

these letters looked a little bit different from those for NIW. All these letters had to emphasize your acheivements and influence in the field were extremely outstanding,peerless,and internation-wide. I did not hire a lawer. All petition and cover letters were done myself. Like my NIW case, all documents were prepared by myself and the case got approved. For my EB1b case, an advisor in international office in the university helped me get a letter from the chair of my department. The employment letter declared that my position was fulltime, sort of permanent. Other documents were copies of those stuffs i prepared for NIW petition.