Here are some books that you can download for free.

• Mark Discroll

  Porn again Christian (A frank discussion on pornography and masturbation) | from Internet Archive https://archive.org/details/Porn-againChristian/mode/2up

• John Piper | Desiring God

  • Don't follow your heart
  • Killjoys | The Seven Deadly Sins
  • Living in the light

• Covenent Eyes Books

  • Your Brain on Porn
  • Hobbies & Habits
  • Porn Circuit
  • Beauty can change your life
  • More than Single: Finding Purpose Beyond Porn

• 9Marks

  • The pastor and pornography

• Challies

  • Sexual Detox - Challies (pdf)