Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
lang van » dang van, tang van, hoang van
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
hanh vai » hanh vi, hanh va, hanh tai
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
vai cua » dai cua, hai cua, lai cua
sach o » sach lo, sac o, mach o
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((sach o) or (sach y)) lang van hoa. hieu va tham thuc van hanh vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((sach o) OR (sach y)) lang van hoa. hieu va tham thuc van hanh vai cua te.
• Adding a wildcard symbol may retrieve word variants: doc ((sach o) or (sach y)) lang van hoa. hieu va tham thuc van hanh vai cua te*.