Of the few that i've seen, the works of S N Swamy is brilliant. His sketches have been compiled into a collection published by the Lalit Kala Akademi a few decades ago. And i don't know whether the book is still available for sale.
It's a beautiful book, with about twenty sketches of some of the famous monuments and sculptures in India. I tried searching for the same on the internet, but sadly, they are very few references to him (except that he's been awarded the Padma Shri in 1969 on a Government Of India web page). And absolutely nothing of his sketches.
For those who would want to see good art, i think S N Swamy will really impress you.