Perhaps you should try some spelling variations:
historia americana » historia mexicana, history american, history americas
lectures field » lectures held, lectures diel, measures field
lectura del » lectura de, lettura del, lecture de

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 (lectura del)) historia americana.
• Adding a wildcard symbol may retrieve word variants: ((lectures field) or (lectura del)) historia americana*.