Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang co » nang cao, nang doc, nang noi
nang ra » nang ma, lang ra, nang ro
cua tu » cua tuc, cua cu, cua te
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang co) or (nang ra)) hoi. hieu quang nam thuc day hanh vi ((cua tu) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang co) OR (nang ra)) hoi. hieu quang nam thuc day hanh vi ((cua tu) OR (cua su)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang co) or (nang ra)) hoi. hieu quang nam thuc day hanh vi ((cua tu) or (cua su))*.