Perhaps you should try some spelling variations:
cham hoi » cham voi, cham h'roi, pham hoai
sach ty » sach tu, sach thu, xach tay
hai cua » thai cua, dai cua, hoi cua
ban hai » ban thai, bang hai, van hai
cham oc » cham soc, cham o, cham voi
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
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 ty) or (sach y)) nang ma hoi. hieu ve ((cham oc) OR (cham hoi)) van ban hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang ma hoi. hieu ve ((cham oc) OR (cham hoi)) van ban hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sach y)) nang ma hoi. hieu ve ((cham oc) OR (cham hoi)) van ban hai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach y)) nang ma hoi. hieu ve ((cham oc) OR (cham hoi)) van ban hai cua tre*.