Legal Contract Needed?

I am in the process of writing a book, which is a compilation of accounts various people have had that are unexplainable, possibly angelic encounters. These were told to me personally and I have asked these people to type their stories and submit the typewritten story to me. I plan to include these stories, along with the names of those who actually had these encounters, in my book. Do I need to have a legal document drawn up by an attorney between myself and these people, or could I type up an agreement myself and let each person sign it, stating that they have given me permission to print their stories and use their names?