1. Go to Finna.fi and perform a search.
2. Narrow the search result to include only theses. Narrow Search > Format > Thesis.
3. For more precise search result, choose a certain type of thesis e.g. Doctoral or Bachelor's (polytechnic). Search result is being refreshed automatically.
Pay attention to availability (holdings information) versus bibliographic information. You see the bibliographic information (for example the university where the thesis was published) by clicking the title of the thesis.