Perhaps you should try some spelling variations:
thanh tap » thanh lap, thanh tai, thanh tay
hieu quan » lieu quan, thien quan, lien quan
su triet » su viet, su tien, ve triet
va thanh » gia thanh, ban thanh, va tinh
cau duc » cao duc, cau luc, cau truc
chu duc » thu duc, chua duoc, cuu duoc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang o » nang co, nang ho, nang ro
tap su » tap suc, thap su, tap tu
o hoi » co hoi, o hoc, o hai

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 nang o hoi. ((hieu quan) or (hieu qua)) ((cau duc) or (chu duc)) va thanh tap su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. ((hieu quan) OR (hieu qua)) ((cau duc) OR (chu duc)) va thanh tap su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. ((hieu quan) or (hieu qua)) ((cau duc) or (chu duc)) va thanh tap su triet*.