Complex sentence: There were also a number of European "bulldog nose" locomotive classes, all of which were built by NOHAB or AFB (with license from EMD), also frequently referred to as "round noses".
Split into simpler sentences: There were also a number of European locomotive classes, all of which were built by NOHAB or AFB (with license from EMD). The European classes are also frequently referred to as "round noses".