Perhaps you should try some spelling variations:
nam thuoc » nam thu, nha thuoc, cay thuoc
hieu van » hieu va, thien van, lieu va
nam thuc » am thuc, nam thu, nam tu
cau tren » cu tren, dau tren, ca tren
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
ve cau » ke cau, va cau, ve cac
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((x hoi) or (xa hoi)). hieu van ((nam thuc) OR (nam thuoc)) va danh ve cau tren~.
• 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 thuc) OR (nam thuoc)) va danh ve cau 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 thuc) OR (nam thuoc)) va danh ve cau tren*".