Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va, hieu qua
dan cua » dan ca, ban cua, dai cua
cua cau » cua cac, cua chu, cua cay
va cam » va cham, va cac, va cao
cam tu » cam thu, nam tu, dam tu
va dan » ca dan, va dao, va dau

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) or (sach ty)) nang cao hoi. hieu va cam tu va dan cua cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang cao hoi. hieu va cam tu va dan cua cau tren.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach ty)) nang cao hoi. hieu va cam tu va dan cua cau tren*.