Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
xa danh » va danh, dia danh, nam danh
tai cua » thai cua, tai cuc, dai cua
qua ca » qua cac, qua cua, qua cai
ca tuc » cua tuc, va tuc

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) OR (doc sach)) ky dang xa hoi. hieu qua ca tuc xa danh ((tai cua) or (tri cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky dang xa hoi. hieu qua ca tuc xa danh ((tai cua) OR (tri cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky dang xa hoi. hieu qua ca tuc xa danh ((tai cua) or (tri cua)) te".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky dang xa hoi. hieu qua ca tuc xa danh ((tai cua) or (tri cua)) te*.