Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
dinh cac » tinh cach, dinh chuc, dinh chau
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
dinh ca » dinh cua, dinh cao, dinh ba
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
me hoi » le hoi
tac va » tac da, tac xa, tuc va

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 y nang ((me hoi) or (ma hoa)). hieu va cac tac va ((dinh ca) OR (dinh cac)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((me hoi) OR (ma hoa)). hieu va cac tac va ((dinh ca) OR (dinh cac)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((me hoi) or (ma hoa)). hieu va cac tac va ((dinh ca) OR (dinh cac)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((me hoi) or (ma hoa)). hieu va cac tac va ((dinh ca) OR (dinh cac)) cuu tre*.