Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
ty lang » tay lang, ty hang, tu lang
hieu va » lieu va, hieu qua
cam tuc » cam xuc, cam tu, nam thuc
va lanh » va lang, va danh, va hanh
dao cua » dai cua, day cua, dan cua
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

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