Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
diem cau » dieu can
dien cau » dien cac, dien cu, dien ca
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
xuc va » duc va, tuc va, luc va
va cam » va cham, va cac, va cao
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, 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 hoc)). hieu va cam xuc va hanh ((dien cau) or (diem cau)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((o hoi) OR (o hoc)). hieu va cam xuc va hanh ((dien cau) OR (diem cau)) treo.
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((o hoi) or (o hoc)). hieu va cam xuc va hanh ((dien cau) or (diem cau)) treo*.