One part of the URL which you found is probably:
The sequence of numbers which follows after /handle/fub188/ is the ID number of the document you are looking for. If you add this ID to the URL https://refubium.fu-berlin.de/handle/fub188/ you will have the URL of the dissertation you are looking for.
The URL of the separate chapter which you found:
The URL leading to the start page with all the metadata belonging of this dissertation: