Perhaps you should try some spelling variations:
las investigacion » la investigacion, las investigaciones, a investigacion
coleccion letras » coleccion las, coleccion libros, coleccion becas
letras las » letras la, letras solas, tras las
las colas » las coplas, las cosas, las olas
las loas » las lajas, las alas, las olas

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( coleccion letras las investigacion ) or ( coleccion ((las loas) OR (las colas)) investigacion ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( coleccion letras las investigacion ) OR ( coleccion ((las loas) OR (las colas)) investigacion )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( coleccion letras las investigacion ) or ( coleccion ((las loas) OR (las colas)) investigacion ))".
• Adding a wildcard symbol may retrieve word variants: (( coleccion letras las investigacion ) or ( coleccion ((las loas) OR (las colas)) investigacion ))*.