As a matter of routine we try to provide direction to help you locate appropriate reference materials to guide you in deciding on version choices when purchasing one of our models. With rolling stock this tends to be more difficult as material does not come in large easily accessed formats, thus is the case with our G22b project. The best single source of background material that we located is listed below. The actual development of this project was done through the use of copies of original railroad tracings and the historical data contained there in.