Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
hanh vai » hanh vi, hanh va, hanh tai
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, me hoi
nam da » nam dan, nam a, nam va
da ban » dia ban, dua ban, day ban

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 nang ((ma hoi) or (ma hoa)). hieu van nam da ban hanh vai ((cau tren) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((ma hoi) OR (ma hoa)). hieu van nam da ban hanh vai ((cau tren) OR (cua tre)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((ma hoi) or (ma hoa)). hieu van nam da ban hanh vai ((cau tren) or (cua tre))*.