Perhaps you should try some spelling variations:
"planes generales" » "plants general", "almacenes generales", "apuntes generales"
"temas generales" » "temas centrales", "temas general", "teorias generales"
"leyes generales" » "leyes general", "leyes federales", "los generales"
"themes general" » "temas general", "theater general", "leyes general"

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: (((("temas generales") OR ((("leyes generales") OR ("planes generales"))))) OR ("themes general"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"temas generales\") or (((\"leyes generales\") OR (\"planes generales\"))))) or (\"themes general\"))~".
• Removing quotes may allow a broader search: (((( temas generales ) or ((( leyes generales ) OR ( planes generales ))))) or ( themes general ))~.
• Adding a wildcard symbol may retrieve word variants: (((("temas generales") or ((("leyes generales") OR ("planes generales"))))) or ("themes general"))*.