deletions | additions       diff --git a/layout.md b/layout.md  index 1e856d9..bb6eeb7 100644  --- a/layout.md  +++ b/layout.md 
...
preface.md  Summary_or_Abstract_of_the__.md  Chapter_2_introduction_and_Background_.md  Chapter_3_Review_of_the__.md  Chater_4_Materials_and_Methods__.md