Perhaps you should try some spelling variations:
dang thai » dang thi, dang hai, dang khai
hieu van » hieu va, thien van, lieu va
thai cua » than cua, tai cuc, tri cua
sach ty » sach y, sach tu, sach thu
va dang » van dang, va nang, va lang
sach ky » sac ky, sach y, sach kem
van dat » van dao, van dau, dan dat
cua te » cua tu
ma hoi » mai hoi, ma hoa, me hoi
nuoc » quoc, duoc, ngoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat ((sach ky) OR (sach ty)) nang ((ma hoi) or (xa hoi)). hieu van dat nuoc va dang thai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach ty)) nang ((ma hoi) OR (xa hoi)). hieu van dat nuoc va dang thai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) OR (sach ty)) nang ((ma hoi) or (xa hoi)). hieu van dat nuoc va dang thai cua te".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) OR (sach ty)) nang ((ma hoi) or (xa hoi)). hieu van dat nuoc va dang thai cua te*.