Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
cua tre » cua te, cua triet, dua tren
hang di » hang doi, hang vi, hang dien
va hang » van hang, va nang, va lang
cam luc » cam xuc, cau luc
cuu tre » cau tren, cau treo
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
luc va » duc va, tuc va, loc va
v nang » va nang, vu nang, van nang
va cam » va cham, va cac, va cao

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)) v nang xa hoi. hieu va cam luc va hang di ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) v nang xa hoi. hieu va cam luc va hang di ((cua tre) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) v nang xa hoi. hieu va cam luc va hang di ((cua tre) OR (cuu tre))*".