Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
van tang » van thang, van trang, van nang
thuc van » thuc vat, thuc dan, thuc va
sach ky » sac ky, sach ty, sach kem
hieu he » hieu ve, hiem he, hieu le
lang xa » lang ha, dang xay, lang van
he nam » ha nam, nghe nam
di su » doi su, ki su, de su
da su » dan su, dat su, va su

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 ky) or (sach y)) lang xa hoi. hieu he nam thuc van tang ((di su) OR (da su)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) lang xa hoi. hieu he nam thuc van tang ((di su) OR (da su)) viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach y)) lang xa hoi. hieu he nam thuc van tang ((di su) OR (da su)) viet*".