Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dang hai » dang khai, hang hai, dung hai
hau treo » cau treo, cau theo, dau tren
su sach » so sach, vu sach
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
cao hoi » cau hoi, cao hoc, tao hoi
thuc va » thuc dan, thuc day
hai hau » hai chau, dai hau, hai hai
co hoi » co hoc, co loi

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 nang ((cao hoi) or (co hoi)). hieu van nam ((thuc va) OR (thuc vat)) dang hai hau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly nang ((cao hoi) OR (co hoi)). hieu van nam ((thuc va) OR (thuc vat)) dang hai hau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly nang ((cao hoi) or (co hoi)). hieu van nam ((thuc va) OR (thuc vat)) dang hai hau treo".
• Adding a wildcard symbol may retrieve word variants: su sach ly nang ((cao hoi) or (co hoi)). hieu van nam ((thuc va) OR (thuc vat)) dang hai hau treo*.