Perhaps you should try some spelling variations:
phap thuc » phap thu, phap hoc, phap tu
day thanh » dao thanh, dat thanh, da thanh
thu tang » thu trang, thu thang, thu bang
thanh va » thanh van, hanh va, thanh ha
thu hang » thi hang, thuc hanh, thu huong
thuc day » thuc dan, thuc vat
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((thu tang) or (thu hang)) ma hoa. ((hieu va) OR (hieu qua)) phap thuc day thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((thu tang) OR (thu hang)) ma hoa. ((hieu va) OR (hieu qua)) phap thuc day thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((thu tang) or (thu hang)) ma hoa. ((hieu va) OR (hieu qua)) phap thuc day thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((thu tang) or (thu hang)) ma hoa. ((hieu va) OR (hieu qua)) phap thuc day thanh va cua tre*.