Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
cac dai » cac dan, cac bai, bac dai
va tinh » may tinh
tinh vi » trinh vi, tinh voi, tinh va
co hoi » co hoc
vi cua » vai cua, di cua

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 ty nang ((co hoi) or (co loi)). hieu van ((cac dai) OR (can dai)) va tinh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang ((co hoi) OR (co loi)). hieu van ((cac dai) OR (can dai)) va tinh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang ((co hoi) or (co loi)). hieu van ((cac dai) OR (can dai)) va tinh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang ((co hoi) or (co loi)). hieu van ((cac dai) OR (can dai)) va tinh vi cua vat*.