Perhaps you should try some spelling variations:
sach nay » sach hay, sach vay, sach nang
dan hanh » dang hanh, dan khanh, dan thanh
sach tay » xach tay, sach hay, sach tai
cao hoc » co hoc, cho hoc, chat hoc
doi cua » dai cua, hoi cua
hieu ke » hieu kem, chieu ke, hieu ky
lang ha » long ha
ke cao » ke cau, ke co, te cao
di cua » dai cua, de cua, do cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach tay) OR (sach nay)) lang ha noi. hieu ke cao hoc dan hanh ((di cua) OR (doi cua)) te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach tay) or (sach nay)) lang ha noi. hieu ke cao hoc dan hanh ((di cua) OR (doi cua)) te~".
• Adding a wildcard symbol may retrieve word variants: thu ((sach tay) or (sach nay)) lang ha noi. hieu ke cao hoc dan hanh ((di cua) OR (doi cua)) te*.