Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
chat vuc » chat xuc, chat va, chat huu
ty hang » ly hang, thi hang, thu hang
cho hoc » co hoc, khoa hoc
hieu ve » hieu va, hieu van
ve chat » va chat, van chat
vuc van » duc van, luc van, thuc van
ty nang » ky nang, ly nang, ty nong
hanh di » hanh vi, hanh de, hang di
cua cau » cua cac, cua chu, cua cay
di cua » dai cua, doi cua, de 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: toc sach ((ty nang) OR (((ty hang) OR (ty xang)))) cho hoc. hieu ve chat vuc van hanh di cua cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) or (((ty hang) OR (ty xang)))) cho hoc. hieu ve chat vuc van hanh di cua cau~".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty nang) or (((ty hang) OR (ty xang)))) cho hoc. hieu ve chat vuc van hanh di cua cau*.