Hathi currently supports a few different ways of obtaining bibliographic citations for items in its digital library.
All can be found by clicking the "Catalog Record" of any HathiTrust title (example below)
You'll then see the following options under the title:
Cite this provides both an APA and an MLA citation to copy/paste as needed.
Export citation file generates a RIS Formatted file for download and use in Endnote; this usually happens seamlessly.
Hathi Catalog citations also import well into Zotero, if you use this open source citation manager.