作さく者しゃ未み詳しょう

noun which may take the genitive case particle 'no'

anonymous; of unknown authorship

Used primarily in bibliographic, academic, or literary contexts to indicate that the author of a work is unknown. Often appears as a descriptor for classical texts, poems, or historical documents.

• この和わ歌かは作さく者しゃ未み詳しょうとされている。

  This waka poem is considered to be of unknown authorship.

• 作さく者しゃ未み詳しょうの古こ文ぶん書しょが多た数すう残のこっている。

  Many ancient documents of unknown authorship remain.