I've reached that point in my preliminary research where I've exhausted most of the published English-language source material, and I'm moving into the realms of Uzbek and Russian publications, more particularly, academic journals.
The initial phase has been to tootle around the stacks of IU Wells Library, plucking volumes, issues or parts of journals from the shelves, flicking through the tables of content, and recording details of relevant articles.
This - children - is bibliographic research the old-fashioned way. The three journals I've most been concerned with in this phase - Sharq Yulduzi [Star of the East), O'zbek tili va adabiyoti (Uzbek Language and Literature) and O'zbekiston tarixi (History of Uzbekistan) - are not readily available electronically (yet...).
However, even with the incomplete sets in the Wells Library, I've identified several dozen likely looking articles which may be of some use, all to do with Nava'i, in some way or other.