Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
cau thuc » cau truc, cuu thuc, can thuc
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
hanh te » hanh tu, hanh ve, hanh de
van cau » van dau, van hau, van chat
tang ma » mang may, tang van
tang ha » lang ha, trung ha, tang van
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
te cua » tue cua, le cua, de cua

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: ((tu sach) OR (so sach)) ky ((tang ha) OR (tang ma)) noi. hieu van cau thuc vat hanh te cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (so sach)) ky ((tang ha) OR (tang ma)) noi. hieu van cau thuc vat hanh te cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (so sach)) ky ((tang ha) OR (tang ma)) noi. hieu van cau thuc vat hanh te cua tre*.