Perhaps you should try some spelling variations:
phat thuc » phap thuc, pham thuc, phan thuc
vat hanh » vat thanh, van hanh, va hanh
hanh hai » thanh hai, nhanh hai, hang hai
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, mang may
hieu va » lieu va, hieu qua
hai cua » thai cua, dai cua, hoi cua
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach thieu ((nang ma) OR (nang cao)) hoi. hieu va phat thuc vat hanh hai cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thieu ((nang ma) OR (nang cao)) hoi. hieu va phat thuc vat hanh hai cua tu".
• Adding a wildcard symbol may retrieve word variants: so sach thieu ((nang ma) OR (nang cao)) hoi. hieu va phat thuc vat hanh hai cua tu*.