Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cam thuc » am thuc, nam thuc, cam thu
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
sua viet » su viet, cua viet, lua viet
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
ky tang » ky nang, ky dang, kho tang
vu sach » vu bach, su sach, vu khach
tai sua » dai sua, tai su, tai cua
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (vu sach)) ky tang ma hoi. hieu va cam thuc van hanh tai sua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (vu sach)) ky tang ma hoi. hieu va cam thuc van hanh tai sua viet.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (vu sach)) ky tang ma hoi. hieu va cam thuc van hanh tai sua viet*.