Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cac khoi » cac thoi, cac khoan, cach thoi
cau tren » cu tren, ca tren, cau treo
danh sai » dung sai, danh bat, danh dau
hieu van » hieu va, thien van, lieu va
dau tren » dau tien, dat tren, dau tieng
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
nam xuc » cam xuc, nam xua, nam thuc
va danh » va dinh, va dan, va hanh
ky tang » ky nang, ky dang, kho tang
xuc va » duc va, tuc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky tang ((mai hoi) or (cac khoi)). hieu van nam xuc va danh sai ((cau tren) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky tang ((mai hoi) OR (cac khoi)). hieu van nam xuc va danh sai ((cau tren) OR (dau tren)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky tang ((mai hoi) or (cac khoi)). hieu van nam xuc va danh sai ((cau tren) or (dau tren))*.