Perhaps you should try some spelling variations:
primare visual » primary visual, primate visual, primate's visual
visual trace » visual track, visual tracker, visual travel
das primare » die primare, das primat
2008 post » 2008 porto, 2008 1st, 2008 pt
2008 21st » 2018 21st
world das » world data, world does, world do

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((2008 post) OR (2008 21st)) world das primare visual trace".
• Adding a wildcard symbol may retrieve word variants: ((2008 post) OR (2008 21st)) world das primare visual trace*.