A friend of mine recently purchased a Polaroid 900 EE Land Camera in working condition. However, there is no manual and we cannot figure out what sort of film to use with the standard back that came with it. Is such film even available? I assume it's 4x5" film loaded into paper sheets (from the looks of the back). If the the film that was used with this camera is no longer available, is there any way to purchase a back that will fit on this camera and that uses a currently available film type? Thanks.