" ' "Do We Have to Know This?" ' "

I am reading a book to my students and have come across something I have never seen. The female character is talking with her brother, so there are double quotes around her dialogue. But then in her dialogue, she is also quoting a famous person. So the sentence looks like this. " ' "It is not for me to say." ' " This brings so many possibilities for writing, so many new ways to annoy readers, so many ways to confound students and trip them up even more in their writings. But I shall not be using it. Some of the students are having enough difficulty with remembering to add the period at the end of the declarative sentence. You are safe for now, dear children.