Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
cau treo » cau theo, cau tren, cau triet
sach ky » sac ky, sach y, sach ty
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
cuu tre » cua tre, cau tren
nam xuc » cam xuc, nam xua, nam thuc
xuc va » duc va, tuc va, luc va
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((o hoi) OR (o hai)). hieu van nam xuc va danh di ((cuu tre) OR (cau treo))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((o hoi) OR (o hai)). hieu van nam xuc va danh di ((cuu tre) or (cau treo))~".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((o hoi) OR (o hai)). hieu van nam xuc va danh di ((cuu tre) or (cau treo))*.