Perhaps you should try some spelling variations:
sach thien » sach thieu, sach tien, cach thien
thien nang » thien bang, thien dang, trien nang
tu sach » thu sach, su sach, te sach
ca tren » cau tren, cu tren, co tren
cua tre » cua te, cuu tre, cua triet
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
la tren » loai tren, dua tren, dat tren
tuc va » thuc va, truc va, tuc xa
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: tu sach thien nang xa hoi. hieu va cam tuc va hanh va ((cua tre) or (((ca tren) OR (la tren))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thien nang xa hoi. hieu va cam tuc va hanh va ((cua tre) OR (((ca tren) OR (la tren)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thien nang xa hoi. hieu va cam tuc va hanh va ((cua tre) or (((ca tren) OR (la tren))))".
• Adding a wildcard symbol may retrieve word variants: tu sach thien nang xa hoi. hieu va cam tuc va hanh va ((cua tre) or (((ca tren) OR (la tren))))*.