The business of inner work is always unique to the individual. Therefore, I find the entire self-help section a waste of time. And to those people who pick up a book (based on Jung, or Campbell, or not) that purports to give them THE answer, they will often be more than disappointed and feel a deeper sense of failure, a deeper sense of marginalization, because they’ve been given the answers and still can’t manage to be happy.
As far as reading and bibliotherapy is concerned, one can’t go wrong with poetry. Mary Oliver, Wallace Stevens, Anne Sexton, Stanley Kunitz, and of course, Rilke.
There are no better psychologists than Shakespeare, Tolstoy, or Virginia Wolfe, and Thomas Mann. Reading them is to open to all sorts of insights about the world and human nature.