You might consider Stranger in the Mirror: Dissociation,the Hidden Epidemic, https://www.amazon.com/Stranger-Mirror-Marlene-M-D-Steinberg/dp/0060954876
and, seeing how you are research oriented, this link to studies of DID that have been based upon use of the diagnostic methods discussed in the Stranger book:
Have you tried this questionnaire? It seems to be the most credible of the online tests, that I know of atleast. It's made by the people who wrote the book "the stranger in the mirror".
Remember that almost everyone (about 75% of people) reports experiencing the symptoms of dpd for brief moments of time. Usually after a traumatic event.
The diagnosis is only given when the symptoms are lasting and disruptive towards work or social interactions.
Don't take the online tests too seriously- don't take me too seriously. If the symptoms of dpd are painful and disruptive then consider contacting a psychologist for help. Furthermore I would recommend this book called overcoming depersonlization disorder
In diagnosing DID, one of the 5 major symptom complexes to consider is derealization. You can read about how that all folds into a possible dissociative disorder diagnosis at: http://www.strangerinthemirror.com/dissociative.html
You may also want to read the book for which that web site is named: https://www.amazon.com/Stranger-Mirror-Marlene-M-D-Steinberg/dp/0060954876