There are a few books on identity in post-unification Germany and an extensive literature during the 1980s. One problem is that there is not a subject heading for German identity as such.
Additional queries welcome.
220 pages with contributions by scholars in Germany and the United States. Erst vereint, nun entzweit. Der Spiegel, Nr. 3, 18. Januar 1993, p.52-62. People's objective situation better than perceived.