So yours truly has been secretly working on a new project - diyethics.com for the past year to compile GS IV Study Material. This was after one of forum members said that forum does not have a good GS IV reference material.
I have also taken some classes on the same and have managed to compile a lot of things in this book.
You can check out the Red Book here . For complete beginners and those appearing this year Mains can use parts of the book to augment their content - or build some good content by using content from this book.
The book is free as of now.
Here is the link!
Take a look, and leave a Thank you Note if you feel it helps solve some problems :)
Where it lacks, please PM me and I shall work on it.
Link to the hardcopy of the Book on Amazon