Is the Bible the only authority?

Protestants, they call themselves Christians. Some of them think that Catholic are not Christians. They do not know that the First 1,000 years Christianity was the Catholic Church. Today, Catholics still are Christians. However, no all Christians are Catholics. Most of the Protestants, especially the ones that want to be faithful to the Protestant roots, believe the Bible the only authority or Sola Scriptura. Any who believe that think that all what they believe is in the Bible, they do not need anything else. However, what they believe, Bible only authority needs to be in the Bible too, as they believe all what they believe is in the Bible. I ask them tell me the book and Bible verse says that or where is that in the Bible. I have not heard any answers yet, just attacks.