Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lien cuc » dien cuc, lien tuc, vien cac
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cuc tre » duc tre, cua tre, cuu tre
va dan » ca dan, va dao, va dap
va dau » va dao
va cam » va cham, va cac, va cao
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang ((o hoi) OR (o hai)). hieu va cam xuc ((va dan) OR (va dau)) lien cuc tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((o hoi) OR (o hai)). hieu va cam xuc ((va dan) OR (va dau)) lien cuc tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((o hoi) OR (o hai)). hieu va cam xuc ((va dan) OR (va dau)) lien cuc tre*.