I found this to be a very good book, a kind of roadmap. The main link to this Google book is
Sikh identity: an exploration of ... - Google Books
These are the contents:
- Who is a Sikh? Historical Perspe...
- Guru Nanak Nishkam Sewak Jatha
- Namdharis
- Ravidasis
- Valmlkis
- Sikh Dharma of the Western Hemis...
- Conclusion
- Illustrations and literature fro...
More to come from my pdf collection and Google books.