Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
hac duc » hoc duc, ha duc, thach duc
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
va hac » van hac, va khac, va cac
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, doi cua, de cua
cua tu » cua tuc, cua su, cua cu

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: ((te sach) OR (toc sach)) ty nang ma hoi. hieu va hac duc ((van hanh) OR (ban hanh)) di cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty nang ma hoi. hieu va hac duc ((van hanh) or (ban hanh)) di cua tu~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ty nang ma hoi. hieu va hac duc ((van hanh) or (ban hanh)) di cua tu*.