Perhaps you should try some spelling variations:
sach nay » sach hay, sach nang, sach ngan
van hanh » van thanh, ban hanh, van anh
sach vay » sach va, sach hay, sach dao
sach tay » xach tay, sach hay, sach tai
khoa hoc » hoa hoc
hoc van » hoc dan, hoc va, hoc vat
hanh di » hanh vi, hanh de, hang di
lang ha » long ha
hieu ke » hieu kem, chieu ke, hieu ky
di cua » dai cua, doi cua, de cua
ha hoi » hoa hoi, ha noi, xa hoi
cua te » cua tu

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) OR (sach vay)))) lang ha hoi. hieu ke khoa hoc van hanh di cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach tay) or (((sach nay) OR (sach vay)))) lang ha hoi. hieu ke khoa hoc van hanh di cua te~".
• Adding a wildcard symbol may retrieve word variants: thu ((sach tay) or (((sach nay) OR (sach vay)))) lang ha hoi. hieu ke khoa hoc van hanh di cua te*.