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
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
cac toc » cac toi, cac nuoc, cac thoi
cac tuc » cac tu, cac tac, cac nuoc
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
la tren » loai tren, dua tren, dat tren
cua te » cua tu

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thien nang xa hoi. hieu va ((cac tuc) OR (cac toc)) va hanh va ((cua te) OR (la tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thien nang xa hoi. hieu va ((cac tuc) OR (cac toc)) va hanh va ((cua te) or (la tren))~".
• Adding a wildcard symbol may retrieve word variants: tu sach thien nang xa hoi. hieu va ((cac tuc) OR (cac toc)) va hanh va ((cua te) or (la tren))*.