Has anyone seen the Sanskrit term nirvāṇa-mastaka in use? It appears in A Dictionary in Sanscrit and English, by H. H. Wilson, 2nd ed., 1832 (not in his 1st ed., 1819), defined simply as "liberation." From there it was copied in the Petersburg Wörterbuch (defined as Erlösung) and in the Monier-Williams dictionary (defined as liberation, deliverance), both of which give only Wilson as their source for this term. It is not in the Śabda-kalpa-druma, but is in the Vācaspatyam, defined as: nirvāṇam nirvṛtir mastakam iva yatra. Various searches by me have so far failed to turn up this term in a Sanskrit text. Hoping that one of you has seen it in use and can give a textual source for it.