Perhaps you should try some spelling variations:
van thang » van thanh, van khang, van hang
thang tai » hang tai, tang tai, thanh tai
sach tay » xach tay, sach hay, sach tai
sach nay » sach hay, sach vay, sach nang
dung xay » dang xay, dung may, dung tay
cuc tieu » muc tieu, cac tieu, cach tieu
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh

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 tay) OR (sach nay)) dung xay hoi. hieu va cac duc van thang tai cuc tieu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach tay) OR (sach nay)) dung xay hoi. hieu va cac duc van thang tai cuc tieu".
• Adding a wildcard symbol may retrieve word variants: so ((sach tay) OR (sach nay)) dung xay hoi. hieu va cac duc van thang tai cuc tieu*.