Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xay » dang xay, nganh xay, nang xuan
anh thai » anh thi, nhanh thai, tranh thai
anh tai » hanh tai, vanh tai, xanh tai
hieu ve » hieu va, hieu van
xay hoi » xa hoi, tay hoi, cay phoi
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
du tan » duc tan, duy tan, du tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky nang xay hoi. hieu ve cac du tan ((anh thai) or (anh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang xay hoi. hieu ve cac du tan ((anh thai) OR (anh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky nang xay hoi. hieu ve cac du tan ((anh thai) or (anh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang xay hoi. hieu ve cac du tan ((anh thai) or (anh tai)) cua tre*.