Civil Registration: Records for Kreis Schleswig are online on FamilySearch.org.
Civil Registration deaths for Altona (3) and Hamburg and surrounding area are on Ancestry.com
History
Histories of places in the Angeln region including parts of Kreis Schleswig can be found in Angeln. Geschichtlich und Topographisch beschrieben by H. N. A. Jensen, 1844. [Family History Library book number 943.512 H2j].
Link to genealogy in Erfde: Erfde.com [includes census records, emigrants, families, etc.