The following has been added to the Zotero Group for Ancient World Open Bibliographies and the Ancient World Open Bibliographies Wiki.
OSU Excavations at Isthmia: Selected References
Unattributed, Ohio State University.
Copyrighted 2000; no items listed date after that.
I would guess this bibliography was prepared to orient students working at the site; it includes major publications about Isthmia as well as some very general works in Greek archaeology.