Perhaps you should try some spelling variations:
tu triet » su triet, tu thiet, tu trien
van hanh » van thanh, ban hanh, van anh
sach ky » sach y, sach ty, sach kem
hanh de » hanh ve, hanh kem
cao suc » cao su
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cao duc » dao duc, giao duc, tao duoc
sac ky » cac ky, sai ky
de tu » do tu

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 ky) or (sac ky)) nang xa hoi. hieu va ((cao duc) OR (cao suc)) van hanh de tu triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang xa hoi. hieu va ((cao duc) OR (cao suc)) van hanh de tu triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang xa hoi. hieu va ((cao duc) OR (cao suc)) van hanh de tu triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang xa hoi. hieu va ((cao duc) OR (cao suc)) van hanh de tu triet*.