Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
tu sach » thu sach, su sach, te sach
ky lang » ky dang, ky tang, tay lang
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
cua tre » cua te, cuu tre, dua tren
ve cac » va cac, vien cac
tuc va » thuc va, truc va, tuc xa
va don » va dong, va doc, va do

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) OR (ky nang)) xa hoi. hieu ve cac tuc va don vi ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve cac tuc va don vi ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve cac tuc va don vi ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve cac tuc va don vi ((cua tre) or (cua triet))*.