Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
hieu van » hieu va, thien van, lieu va
thuoc va » thuc va, thuoc ma, thuong va
cau tren » cu tren, dau tren, cau treo
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va danh » va dinh, va dan, va hanh
danh ve » dinh ve, hanh ve, anh ve
ca tren » cu tren, la tren, co tren
x hoi » o hoi, x ho, 5 hoi

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: tu sach ky nang ((x hoi) OR (xa hoi)). hieu van nam thuoc va danh ve ((cau tren) OR (ca tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (xa hoi)). hieu van nam thuoc va danh ve ((cau tren) OR (ca tren))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (xa hoi)). hieu van nam thuoc va danh ve ((cau tren) OR (ca tren))*.