Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, dang xay, lang van
vat dan » va dan, van dan, vat ran
cua tre » cua te, cuu tre, cua triet
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((lang xa) or (van xay)) hoi. hieu quang nam thuc vat dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((lang xa) OR (van xay)) hoi. hieu quang nam thuc vat dan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((lang xa) or (van xay)) hoi. hieu quang nam thuc vat dan vi cua tre*.