Perhaps you should try some spelling variations:
tecnicas didacticas » tecnica didactica, tecnicas practicas, secuencias didacticas
unidas didacticas » unidades didacticas, unidad didactica, una didactica
guias didacticas » guia didactica, las didacticas, una didactica
guias practicas » guia practica, unas practicas, algunas practicas

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

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