Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
nam thuc » nam thuoc, am thuc, nam thu
quan nam » quang nam, xuan nam, quan am
cau treo » cau theo, cau tren, cau triet
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
sach ky » sac ky, sach y, sach kem
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, den vai
dan vat » dang vat, van vat, dan va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((sach ky) OR (sach ty)) nang xa hoi. hieu quan nam thuc va ((dan vai) or (dan vat)) cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach ty)) nang xa hoi. hieu quan nam thuc va ((dan vai) OR (dan vat)) cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ky) OR (sach ty)) nang xa hoi. hieu quan nam thuc va ((dan vai) or (dan vat)) cau treo".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) OR (sach ty)) nang xa hoi. hieu quan nam thuc va ((dan vai) or (dan vat)) cau treo*.