Perhaps you should try some spelling variations:
va hanh » van hanh, va thanh, va danh
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cac dac » cac dan, cac dai, cac bac
sac ky » cac ky, sai ky
dac va » duc va, day va, dat va
di su » doi su, da su, de su
ki su » ky su

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 tu) or (sac ky)) nang xa hoi. hieu va cac dac va hanh ((di su) or (ki su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sac ky)) nang xa hoi. hieu va cac dac va hanh ((di su) OR (ki su)) triet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) or (sac ky)) nang xa hoi. hieu va cac dac va hanh ((di su) or (ki su)) triet*.