Begin with a keyword search, for example:
Turkish AND German*
immigra* AND German*
transnational* AND German*
migra* AND German*
multicultural* AND German*
(Note that the * is a truncation symbol, e.g. immigra* returns results for immigrant, immigrants, immigration, etc.)
When you find an article that looks relevant and useful, take a look at the subject headings. You can use this phrase to run a new search. There are two main advantages to continuing your search using subject headings:
1. They may help you find items that did not come up in your initial keyword search.
2. The subject headings can give you ideas of additional words to use in your keyword searches.