Perhaps you should try some spelling variations:
lectures field » lectures held, lectures diel, measures field
lectures de » lectures _, lectures 1, lectures a
lectures 2 » lectures _, lectures 1
lecture de » lecture _, lecture 1, lecture 2

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((((lectures field) OR (((lectures de) OR (lectures 2))))) OR (lecture de)) historia (mexicana* OR americana*).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((lectures field) or (((lectures de) OR (lectures 2))))) or (lecture de)) historia (mexicana* or americana*)".
• Adding a wildcard symbol may retrieve word variants: ((((lectures field) or (((lectures de) OR (lectures 2))))) or (lecture de)) historia (mexicana* or americana*)*.