diff --git a/pdf/16. Ethical Hacking and Countermeasures.pdf b/pdf/16. Ethical Hacking and Countermeasures.pdf new file mode 100644 index 0000000..456e05c Binary files /dev/null and b/pdf/16. Ethical Hacking and Countermeasures.pdf differ diff --git a/pdf/17. Reversing - Secrets of Reverse Engineering.pdf b/pdf/17. Reversing - Secrets of Reverse Engineering.pdf new file mode 100644 index 0000000..629f249 Binary files /dev/null and b/pdf/17. Reversing - Secrets of Reverse Engineering.pdf differ diff --git a/pdf/18. Network Security Bible.pdf b/pdf/18. Network Security Bible.pdf new file mode 100644 index 0000000..57f2afd Binary files /dev/null and b/pdf/18. Network Security Bible.pdf differ diff --git a/pdf/19. Hacking Web Applications - Hacking Exposed.pdf b/pdf/19. Hacking Web Applications - Hacking Exposed.pdf new file mode 100644 index 0000000..c2e2358 Binary files /dev/null and b/pdf/19. Hacking Web Applications - Hacking Exposed.pdf differ diff --git a/pdf/20. Hacking for Dummies.pdf b/pdf/20. Hacking for Dummies.pdf new file mode 100644 index 0000000..0fa6746 Binary files /dev/null and b/pdf/20. Hacking for Dummies.pdf differ