http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
"An argument for a novel binarity constraint on merge, preventing syntactic movement from relating more than two distinct positions at one time"--
Barbara Citko and Martina Gračanin-Yüksek.
Includes bibliographical references (pages 159-169) and index.