Perhaps you should try some spelling variations:
sach tay » xach tay, sach hay, sach tai
thanh va » thanh van, hanh va, thanh ha
va thanh » gia thanh, ban thanh, va tinh
sach nay » sach hay, sach vay, sach nang
cau duc » cao duc, cau luc, chu duc
hieu va » lieu va, hieu qua
hieu ve » hieu van
cua tre » cua te, cuu tre, cua triet
lang ha » long ha
ha hoi » hoa hoi, ha noi, xa hoi
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: thuat ((sach tay) OR (sach nay)) lang ha hoi. ((hieu ve) or (hieu va)) cau duc va thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach tay) OR (sach nay)) lang ha hoi. ((hieu ve) OR (hieu va)) cau duc va thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach tay) OR (sach nay)) lang ha hoi. ((hieu ve) or (hieu va)) cau duc va thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach tay) OR (sach nay)) lang ha hoi. ((hieu ve) or (hieu va)) cau duc va thanh va cua tre*.