Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
cam thuc » am thuc, nam thuc, cam thu
hau tren » cau tren, thai tren, chay tren
danh hai » dang hai, lanh hai, manh hai
hieu van » hieu va, thien van, lieu va
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
sach lo » sach dao, sach doi, sach hoi
lo nang » ho nang, ly nang, loai nang
van cam » van nam, van lam, van cau
ma hoi » mai hoi, ma hoa, me hoi

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 lo nang ((ma hoi) or (xa hoi)). hieu van cam thuc va danh hai ((hau tren) OR (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach lo nang ((ma hoi) OR (xa hoi)). hieu van cam thuc va danh hai ((hau tren) OR (dau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach lo nang ((ma hoi) or (xa hoi)). hieu van cam thuc va danh hai ((hau tren) OR (dau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach lo nang ((ma hoi) or (xa hoi)). hieu van cam thuc va danh hai ((hau tren) OR (dau tren))*.