While there exist documentation of some WIMAX certified equipment and private training, WIMAX remains unknown in a hands-on sense. Internationally, WIMAX versions have been out for several years with deployment figures from 60,000 to 90,000 systems across the four WIMAX certified equipment vendors thus far. Hands-on engineering training remains difficult to find or obtain. In the United States, the number of WIMAX deployments is probably less than 10% of the international figures. While you can run out and purchase reference books on standards and regulations surrounding WIMAX, you cannot as easily purchase real "how to" books on WIMAX, especially in the United States, simply because it is much too new and still unsettled.