Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
va hanh » van hanh, va thanh, va danh
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
xang x » nang x
hai du » hai vu, hai di, hai xu
tai du » tai tu, tri du, tai su
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (thuat sach)) ty xang x hoi. hieu van ((hai du) OR (tai du)) va hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (thuat sach)) ty xang x hoi. hieu van ((hai du) OR (tai du)) va hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu hoach) or (thuat sach)) ty xang x hoi. hieu van ((hai du) OR (tai du)) va hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (thuat sach)) ty xang x hoi. hieu van ((hai du) OR (tai du)) va hanh tai cua tre*.