Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cham loc » cham soc, chon loc, hau loc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
va nang » van nang, da nang, cam nang
v nang » vu nang, van nang, voi nang
cham o » cham soc
va dan » ca dan, va dao, va dau
dan de » dan den, dang de, van de
de cua » le cua, te cua, dieu cua

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 ((v nang) or (va nang)) xa hoi. hieu ve ((cham loc) or (cham o)) va dan de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (va nang)) xa hoi. hieu ve ((cham loc) OR (cham o)) va dan de cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (va nang)) xa hoi. hieu ve ((cham loc) or (cham o)) va dan de cua tre*.