I am not sure about a website for this regiment, but no book has a picture of it that I am aware of. There is the flag of the 4th Missouri Infantry of the same Van Dorn pettern that is depicted in the book "Arms & Equipment of the Confederacy," on Page 260.
These were the first Van Dorn pattern battle flags isseued. They were made by the ladies of Guntown, MS. and given to the Missouri Brigade in June, 1862. They are the only Van Dorn flags with fringe (save for the 15th NW Arkkansas') and the star pattern was different from the Van Dorn flags that would be issued in August, 1862. The latter's stars were in the more familiar 3-2-3-2-3 arrangement from top to bottom.
The 6th Missouri flag is privately owned I believe and on loan to the National Park Service visitor's center at Corinth.
The crescent on the Van Dorn flags was taken from the Missouri state Coat of Arms as a way to lure more Missouri men into the Confederate Army.