Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cau treo » cau theo, cau triet, cau trieu
danh hai » dang hai, lanh hai, manh hai
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
su sach » so sach, vu sach
ma hoi » xa 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 ky nang ((ma hoi) or (mai hoi)). hieu van nam thuc va danh hai ((cau treo) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((ma hoi) OR (mai hoi)). hieu van nam thuc va danh hai ((cau treo) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((ma hoi) or (mai hoi)). hieu van nam thuc va danh hai ((cau treo) or (cau tren))*.