Perhaps you should try some spelling variations:
"un misterio por resolver gastritis idiopatica juvenil" » "un misterio del resolver gastritis idiopatica juvenil" (Expand Search), "un misterio para resolver gastritis idiopatica juvenil" (Expand Search), "el misterio por resolver gastritis idiopatica juvenil" (Expand Search)
"Un misterio de resolver artritis idiopática juvenil" » "Un misterio del resolver artritis idiopática juvenil" (Expand Search), "Un ministerio de resolver artritis idiopática juvenil" (Expand Search), "Un magisterio de resolver artritis idiopática juvenil" (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("Un misterio de resolver artritis idiopática juvenil") OR ("un misterio por resolver gastritis idiopatica juvenil"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"Un misterio de resolver artritis idiopática juvenil\") OR (\"un misterio por resolver gastritis idiopatica juvenil\"))".
• Removing quotes may allow a broader search: (( Un misterio de resolver artritis idiopática juvenil ) OR ( un misterio por resolver gastritis idiopatica juvenil )).
• Adding a wildcard symbol may retrieve word variants: (("Un misterio de resolver artritis idiopática juvenil") OR ("un misterio por resolver gastritis idiopatica juvenil"))*.