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

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