But fortunately, you've found some actual evidence, so we can start to get somewhere. The book you cite says, "Block later claimed that its central idea of a father and daughter shipwrecked in space was lifted from his favourite play, William Shakespeare's The Tempest
...". That's a beginning, at least. Of course, a claim made after the fact isn't completely authoritative -- this whole thread demonstrates that such claims often distort the facts. In the name of the fact-checking that this thread is about, it would help to have corroboration from an independent source.