Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
thuc dan » thuc hanh, hoc dan
va triet » va thiet, va trien, ve triet
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
dan dai » dat dai, can dai, dan dat
co hoi » co hoc
dai va » mai va
va am » va lam, va cam

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 ((co hoi) OR (co loi)). hieu va am ((thuc dan) OR (thuc vat)) dan dai va triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((co hoi) OR (co loi)). hieu va am ((thuc dan) or (thuc vat)) dan dai va triet~".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((co hoi) OR (co loi)). hieu va am ((thuc dan) or (thuc vat)) dan dai va triet*.