Perhaps you should try some spelling variations:
trinh viet » ninh viet, trinh vat
sach thuc » cach thuc, sach thu, sach thue
hanh than » hanh han, hanh nhan, hanh phan
thu sach » tu sach, thuat sach, thuoc sach
thi hanh » thi thanh
than luc » nhan luc, than duc, thanh luu
va trinh » van trinh, va tinh, lap trinh
viet cau » viet chau, viet ca, viet chu
cau tre » cau tren, cau treo, cau tra
va hoi » xa hoi, va hoc, va hoa
luc va » duc va, tuc va, loc 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 thuc hanh ((va hoi) or (van hoa)). thi hanh than luc va trinh viet cau tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach thuc hanh ((va hoi) OR (van hoa)). thi hanh than luc va trinh viet cau tre.
• Adding a wildcard symbol may retrieve word variants: thu sach thuc hanh ((va hoi) or (van hoa)). thi hanh than luc va trinh viet cau tre*.