diff --git a/04.Basic_Concepts_III.pdf b/04.Basic_Concepts_III.pdf
index 8d945f3..ba6413d 100644
Binary files a/04.Basic_Concepts_III.pdf and b/04.Basic_Concepts_III.pdf differ
diff --git a/05.Basic_Concepts_IV.pdf b/05.Basic_Concepts_IV.pdf
index 7e15e38..9065719 100644
Binary files a/05.Basic_Concepts_IV.pdf and b/05.Basic_Concepts_IV.pdf differ