Input (grade 13): Other significant publications include the AOU Checklist of North American Birds, which is the standard reference work for the field, and a monograph series, Ornithological Monographs.
Output (grade 10): Some of its other big publications are the AOU Checklist of North American Birds and a series, Ornithological Monographs. The AOU Checklist of North American Birds is the standard reference for the field.