He is unable to sign his work, and thus remains nameless.
He usually signed his work in the right hand bottom corner.
His daughter later became the first to sign her work.
He never signed his work, because they weren't that kind of pieces.
After a few years, he stopped signing his work in prison.
"They said if you sign your work, you'll come back."
So he signed his work only on the back.
He sometimes signed his work in pencil on the back.
Since he did not sign his work, his true name is unknown.
They do not sign their work; only the group is identified.