Find literature at the library. Remember that we have a school library on KG with attached librarian who can help you with the search. You will mainly base your IA on printed literature, ie books, and only secondarily on material from the web. You will typically need three to four books and sources. Be critical! Not everything that you think is good, is reliable and suitable. You will typically use material that is written for secondary education, but it's fine if you also use more "academic" literature. Avoid school books. Avoid literature by authors who are not professional historians.
Search Process:
Search for books, sources and articles (see http://skrivopgave.kk.dk/artikel/biblioteket-0)
Search using keywords (eg, from your question) https://library.leeds.ac.uk/researcher-literature-search-guide & https://thesiswhisperer.com/2015/05/13/how-to-become-a-literature-searching-ninja/ & http://skrivopgave.kk.dk/artikel/biblioteket-0
Search in your local library base (http://www.koldingbib.dk/)
Search for more in the national library base (www.bibliotek.dk & http://alvis-bib.sdu.dk/uhtbin/cgisirsi/x/SIRSI/0/57/60/81/X?user_id=WEBSERVER)
Look in the books in the library and check the "hidden bibliographies" in the borrowed books
Search sources (eg www.bibliotek.dk & http://alvis-bib.sdu.dk/uhtbin/cgisirsi/x/SIRSI/0/57/60/81/X?user_id=WEBSERVER & https://arkiv.dk/ & http://www.historisktidsskrift.dk/links.htm & http://danmarkshistorien.dk/kilder/ & https://www.sa.dk/k/brug-arkivet & http://www.kbharkiv.dk/sog-i-arkivet/kilder-pa-nettet & https://sites.google.com/site/gghistorie/empiri/arkiver-med-historiske-%20sources & http://www2.statsbiblioteket.dk/mediestream/) & http://historiskmetode.weebly.com/kilder-og-statistik.html & http://sourcebooks.fordham.edu/index.asp & http://www.gutenberg.org/catalog/ & http://avalon.law.yale.edu/imt/nsdappro.asp
Google Scholar: https://scholar.google.dk/
DEFF PROJECT: http://gymnasium.summon.serialssolutions.com/#!/ & http://www.deff.dk/
For Tutorial see "Help" in "Menu" on http://gymnasium.summon.serialssolutions.com/#!/
Search Kolding history (eg http://stadsarkiv.kolding.dk/koldings-historie & https://www.kulturarv.dk/mussam//VisMuseum.action?museumId=229 & http://www.arkiv.dk/)
Search quality assessed sources via school-oriented web portals (eg. Www.emu.dk or www.infoguide.dk)
An exampel of a definition of primary and secondary sources: https://library.ithaca.edu/sp/subjects/primary