Percy Newberry's series of notebooks includes notebooks on single subjects, indexed notebooks on a range of subjects and research journals. Many of the notebooks have been numbered (in the form NB followed by a number) by Newberry and are referenced elsewhere in his research notes. As such it appears that these notebooks were used as reference books by Newberry, and they often include lists of bibliographic references for a subject.

Unfortunately it is evident that this series of notebooks is not complete and there are numbered notebooks referred to in Newberry's research material that do not appear to be in the collection.