Ok, it’s not a judicial opinion or a research paper, but it seems relevant enough.
Here’s a specimen of a non-disclosure agreement apparently used by the Trump campaign. The names have been redacted.
The document first appeared in The Texas Tribune on March 19, 2018.
Update: Bradley P. Moss at LawFare has a great commentary: Why the White House Can’t Stop Omarosa Manigault-Newman From Talking.
Update II: The Washington Post has additional commentary about the extent of the enforceability of the NDA.