Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
va cam » va cham, va cac, va cao
xuc va » duc va, tuc va, xac va
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
tu cuu » tu huu, tu cua, tu chu

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 y nang xa hoi. hieu va cam ((xuc va) OR (luc va)) dan ((du cuu) or (tu cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. hieu va cam ((xuc va) OR (luc va)) dan ((du cuu) OR (tu cuu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang xa hoi. hieu va cam ((xuc va) OR (luc va)) dan ((du cuu) or (tu cuu)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu va cam ((xuc va) OR (luc va)) dan ((du cuu) or (tu cuu)) tre*.