Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
hieu van » hieu va, thien van, lieu va
dang hai » dang khai, hang hai, dung hai
danh hai » lanh hai, manh hai, danh hau
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
sach ly » sach y, sach lo, sach ty
ly vang » ly hang, ly van, ly quang
ma hoi » mai hoi, ma hoa, me hoi
van am » van nam, van lam, van dam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ly vang ((ma hoi) OR (xa hoi)). hieu van am thuc va ((danh hai) or (dang hai)) cau theo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly vang ((ma hoi) OR (xa hoi)). hieu van am thuc va ((danh hai) OR (dang hai)) cau theo*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly vang ((ma hoi) OR (xa hoi)). hieu van am thuc va ((danh hai) or (dang hai)) cau theo*".