Peter D. Usher Professor Emeritus Breadcrumb About pxu1 Peter Usher Professor Emeritus Department Affiliations Department of Astronomy and Astrophysics Interests Perturbation theory. Quasars. Science and Shakespeare. Email pxu1@psu.edu Phone 412-735-3914 Website http://personal.psu.edu/pxu1/ Follow https://orcid.org/0000-0003-1507-120X https://scholarsphere.psu.edu/collections/sqv33rx85k https://scholarsphere.psu.edu/collections/nzs25x876d
