Five sources for informational text or research material are:
1) Books 2) Periodicals & Newspapers 3) Reliable Articles (both written or internet) that are not always one-sided 4) Documentaries 5) Historical records
Explanation : As described in the above lines Heigl is trying to face her fears in public by speaking the feelings what she is experiencing within herself. She is building her confidence by openly expressing and facing the fears within her.