There isn't a book or single publication on this subject, unfortunately. The key reference is the C28x CPU and instruction set user's guide:
http://www.ti.com/lit/ug/spru430f/spru430f.pdf

This covers the instructions for the fixed-point C28x CPU. For the extended instruction sets, refer to:
http://www.ti.com/lit/ug/spruhs1b/spruhs1b.pdf

Attached are two appendices from the original F2812 three-day training workshop, where the key topics of assembly programming were introduced. Regret I don't know of any other resource.

Regards,

Richard

C28x Workshop - apx B and C.pdf

Actually, my aim is to write my custom serial boot loader so any document for same ??

Grab the bootloader code from controlSUITE and open in in CCS and take a look around how it is implemented.

As you'll see majority of the bootloader was written in C, and I highly recommend you go the same route.

Are you telling about, 

C:\ti\c2000\C2000Ware_1_00_06_00\device_support\f2837xs\examples\cpu1\F2837xS_sci_flash_kernel\cpu01.

No, look into

C:\ti\c2000\C2000Ware_1_00_02_00\libraries\boot_rom\...