Poole and the Cumulative are of little use without a fair assortment of the sets therein indexed.
"Thus far 442 titles (practically all of them serials published since 1800) have been indexed.

It is a mistake, however, to suppose that most of these are necessary in a small library before Poole's index should be purchased or can be of use.

Given Poole and a complete set of Littell's living age, and Harper's monthly, more reference work can be done than with twice the number of reference books not periodicals.
A small collection of sets has enabled more than one struggling library to hold its own with the students and club members, and to accomplish work which could not have been done as well with many works of reference, the purchase of which would have exhausted the whole book fund.".