Perhaps you should try some spelling variations:
sang tao » hang tai
cac thoi » cac toi, cac hop, cac tro
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
tao hoi » tao khoi, tao boi, tay hoi
hieu ve » hieu van
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
cac tu » cac thu, cach tu, cac du
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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 sang tao hoi. ((hieu ve) or (hieu va)) ((cac tu) or (cac thoi)) va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang tao hoi. ((hieu ve) OR (hieu va)) ((cac tu) OR (cac thoi)) va dan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang tao hoi. ((hieu ve) or (hieu va)) ((cac tu) or (cac thoi)) va dan vi cua tre*.