Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
cham thuc » nham thuc, pham thuc, tham thuc
hang cao » hoang cao, nang cao, hang ca
ty hang » ly hang, ty xang, thi hang
cao hoi » cau hoi, co hoi, cao hoc
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
va dan » ca dan, va dao, va dau
vai va » mai va, dai va, hai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (thuat sach)) ty hang cao hoi. hieu vu cham thuc va dan vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (thuat sach)) ty hang cao hoi. hieu vu cham thuc va dan vai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (thuat sach)) ty hang cao hoi. hieu vu cham thuc va dan vai va thiet*.