Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
hieu van » hieu va, thien van, lieu va
hanh tai » hang tai, han tai, hinh tai
tu cach » tu cac
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky nang ma hoi. hieu van nam thu xe ((hanh tai) OR (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang ma hoi. hieu van nam thu xe ((hanh tai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky nang ma hoi. hieu van nam thu xe ((hanh tai) OR (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang ma hoi. hieu van nam thu xe ((hanh tai) OR (thanh tai)) cua tre*.