"Many writers... have written stories directly inspired by other stories. SF is a genre in an ongoing conversation with itself.... [S]tories that annoy can be of more use to the writer than those that are perfectly enjoyable."--Lisa Tuttle, Writing Fantasy and Science Fiction
Note: A solid book on the field. The unique strength or value of this book is its analyses. Her advice is familiar but when she breaks down her work or those of others, you'll want to listen.