As a librarian, I would caution against filtering by publisher. Publishers change their names constantly and have multiple variations. (Harper, HarperCollins, HarperSanFrancisco, Harper San Francisco, Harper Ebooks is one example.) Publishers are also frequently merging/being acquired/being sold to other publishers. Sometimes the original publisher name continues as "an imprint of...." but you can never guarantee how Amazon (or your local library) will input the publisher's data into their system. This would be a never-ending frustration for EYB's database management.
However, book series are fairly consistent. Series were traditionally managed by the U.S. Library of Congress (and the British Library, Library & Archives Canada, National Library of Australia, etc.), so there is more standardization.