"A cloud is hanging above the letters of Flip Slier.... He is aware of it, but we, readers sixty years after the Holocaust, are certainly aware of the clouds of destruction. We experience it with reading Anne Frank's diary; we experience it with the letters of Flip Slier, letters from the heart, letters to cheer up his parents still living in Amsterdam, letters with hope, and letters with fear for the future. Hidden Letters is a salute to a destroyed youth, full of life and spirit."
- David Barnouw
Author, The Definitive & Critical Edition of Anne Frank & Who Betrayed Anne Frank?