Perhaps you should try some spelling variations:
hieu tuc » hieu thuc, hieu luc, hieu thuoc
danh vai » danh sai, danh va, doanh van
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
hau tuc » cau truc, thai tuc
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
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 ((hau tuc) OR (hieu tuc)) va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (xa hoi)). hieu van ((hau tuc) OR (hieu tuc)) va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (xa hoi)). hieu van ((hau tuc) OR (hieu tuc)) va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (xa hoi)). hieu van ((hau tuc) OR (hieu tuc)) va danh vai cua tre*.