Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
hanh doi » thanh doi, hanh noi, hang doi
cam thuc » am thuc, nam thuc, cam thu
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
su viet » so viet
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
doi su » oi su, don su, voi 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 ty ((nang xa) or (lang xa)) hoi. ((hieu van) OR (hieu va)) cam thuc va hanh doi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (lang xa)) hoi. ((hieu van) OR (hieu va)) cam thuc va hanh doi su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (lang xa)) hoi. ((hieu van) OR (hieu va)) cam thuc va hanh doi su viet*".