Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
thanh hoi » thanh hoai, thanh hoa, thanh hai
xach tay » canh tay
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
nam duoc » nam thuoc, da duoc, dat duoc
duoc tan » duc tan, duoc ban, duoc dan
nang ma » tang ma, sang ma, nang cao
hoi cua » hoi chuc
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: so ((xach tay) or (sach thu)) nang ma hoi. hieu van nam duoc tan thanh hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((xach tay) OR (sach thu)) nang ma hoi. hieu van nam duoc tan thanh hoi cua tre.
• Adding a wildcard symbol may retrieve word variants: so ((xach tay) or (sach thu)) nang ma hoi. hieu van nam duoc tan thanh hoi cua tre*.