Perhaps you should try some spelling variations:
based presentation » based representation, case presentation, brief presentation
presentation als » presentation talk, presentation des, presentation av
crops course » crash course, from course, prep course
class course » class case, class cori, class four
als studies » cass studies, css studies, ias studies

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

• Performing a fuzzy search may retrieve terms with similar spellings: commercial ((crops course) OR (class course)) based presentation als studies.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "commercial ((crops course) OR (class course)) based presentation als studies.".
• Adding a wildcard symbol may retrieve word variants: commercial ((crops course) OR (class course)) based presentation als studies.*.