Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
va nang » van nang, da nang, cam nang
va lang » hoa lang
cuu tre » cua tre, cau tren, cau treo
qua coc » qua cac, qua co, qua con
xay hoi » xa hoi, tay hoi, cay phoi
sach v » sach va, sach y, sach 2
v dang » vu dang, va dang, 2 dang
cua te » cua tu

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 dang xay hoi. hieu qua coc luc ((va nang) or (va lang)) di ((cua te) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v dang xay hoi. hieu qua coc luc ((va nang) OR (va lang)) di ((cua te) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach v dang xay hoi. hieu qua coc luc ((va nang) or (va lang)) di ((cua te) or (cuu tre))*.