Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dien cuc » dien tu, dieu cua, vien cac
va nang » van nang, da nang, cam nang
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
cuc tre » duc tre, cua tre, cuu tre
soc va » loc va, doc va, goc va
x hoi » xa hoi, o hoi, x ho

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)) va nang x hoi. hieu vu cham ((soc va) or (hoc va)) tinh dien cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) va nang x hoi. hieu vu cham ((soc va) OR (hoc va)) tinh dien cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) va nang x hoi. hieu vu cham ((soc va) or (hoc va)) tinh dien cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) va nang x hoi. hieu vu cham ((soc va) or (hoc va)) tinh dien cuc tre*.