Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
cau treo » cau theo, cau triet, cau trieu
danh hai » dang hai, lanh hai, manh hai
va danh » va dinh, va dan, va hanh
cam tuc » cam xuc, cam tu, nam thuc
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
van cam » van nam, van lam, van cau
tuc va » thuc va, truc va, tuc xa
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 cam tuc 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 cam tuc va danh hai ((cau treo) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((ma hoi) OR (mai hoi)). hieu van cam tuc 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 cam tuc va danh hai ((cau treo) or (cau tren))*.