Perhaps you should try some spelling variations:
nhieu viec » hieu viec, nhien viet
tinh doi » trinh doc, trinh do, tinh hoc
viec cam » viec lam, viec cua, viec va
tinh di » trinh di, tinh da, tin di
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
lang ha » long ha
lang xa » dang xay, lang van
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((lang xa) or (lang ha)) hoi. nhieu viec cam xuc va ((tinh di) OR (tinh doi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang xa) OR (lang ha)) hoi. nhieu viec cam xuc va ((tinh di) OR (tinh doi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((lang xa) or (lang ha)) hoi. nhieu viec cam xuc va ((tinh di) OR (tinh doi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang xa) or (lang ha)) hoi. nhieu viec cam xuc va ((tinh di) OR (tinh doi)) cua tre*.