Note that many of these are collected works and the individual titles of plays or poems may not be listed in the catalog record. You may need to physically check an index volume or table of contents to find the specific piece you are looking for.
You may also search in Google Books. Copyright restrictions may prevent you from seeing the entire book online, but this works as an online index to books you can then find in the library. The advanced search is more precise.
JSTOR provides online access to many journals, including some in which Brecht's works have been published.
We also have print indexes to poems, short stories, and plays published in collections or in periodicals. If you have trouble finding what you need, contact me and I'll help you use these.
To find works published contemporaneously with historic events, use MERLIN and other library catalogs.
Thanks to DDR-Presse, we have access to online editions of 3 major GDR newspapers: Neues Deutschland, Berliner Zeitung, and Neue Zeit. Scroll down the page to set up a free account.
Otherwise we do not have good online coverage from around 1920 to around 1980.
The Reader's Guide Retrospective indexes news magazines and other sources from 1890 to 1982, but has no full text.