Here is another book that will be useful to those who want to learn more about Gurbani Grammar, its by Bhai Sahib Gyani Harbans Singh Ji called 'Naveen Gurbani Vyakarn'.
This book is in contrast with the more popular Prof. Sahib Singh Ji's Gurbani Vyakarn *link below*, because whereas Prof sahib's book is academic and advanced (and very dry If i be honest ), this one gradually picks up pace and will surprisingly keep you engaged with its small, easy to digest chapters.
I found the sections on the usage of Maatras, and the chapter on importance of correct Gurbani pronounciation particularly interesting. Gyani Ji's approach isn't strictly academic, and unlike Prof. Sahib Singh Ji Gyani Ji is willing to accept that while Gurbani Grammar is an important field of study, it is irrelevant to those individuals whose surat is gone above and beyond the worldly knowledge.. He also refers a lot to Pandit Kartar Singh Dhaaka, and Taksaali Gurmukh Pyaare in the text, and it seems like hes tried to bridge the gap between grammarians and spiritualists with this book..
Anyway, enough of my nonsense Here's the link to the book!
PS: I normally don't make notes on any of my books as I like to keep them virgin but this one has few marks here n there, many apologies for that jeo And.. please dont ask for download links, buy the book instead and support the author!
Prof. Sahib Singh's book: