Perhaps you should try some spelling variations:
cac treo » cau treo, cac trieu, cac tieu
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
tu sach » thu sach, su sach, te sach
ve cham » va cham, ve chat, vu cham
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
ve cam » ve cac, va cam, ve cai
ma hoi » mai hoi, xa hoi, ma hoa

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 ky nang ma hoi. hieu ((ve cam) or (ve cham)) thuc van hanh tai ((cac treo) or (cac tro))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu ((ve cam) OR (ve cham)) thuc van hanh tai ((cac treo) OR (cac tro)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((ve cam) or (ve cham)) thuc van hanh tai ((cac treo) or (cac tro))*.