Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
phap thuc » phap thu, phap hoc, phap tu
hanh hai » thanh hai, nhanh hai, hang hai
vat hanh » vat thanh, van hanh, va hanh
sach thu » sach thieu, sach tham, cach thuc
hai cua » thai cua, dai cua, hoi cua
ve phap » va phap, de phap, ve phan
hieu ve » hieu va, hieu van
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
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 thu) or (sach thue)) ((nang ma) or (sang ma)) hoi. hieu ve phap thuc vat hanh hai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach thu) OR (sach thue)) ((nang ma) OR (sang ma)) hoi. hieu ve phap thuc vat hanh hai cua tu.
• Adding a wildcard symbol may retrieve word variants: so ((sach thu) or (sach thue)) ((nang ma) or (sang ma)) hoi. hieu ve phap thuc vat hanh hai cua tu*.