Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh va » thanh van, hanh va, thanh ha
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
tac xa » tuc xa
o hoc » co hoc, mo hoc, so hoc

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) or (thu sach)) ty nang o hoc. hieu ve cac ((tac xa) OR (tac da)) thanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang o hoc. hieu ve cac ((tac xa) OR (tac da)) thanh va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty nang o hoc. hieu ve cac ((tac xa) OR (tac da)) thanh va su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty nang o hoc. hieu ve cac ((tac xa) OR (tac da)) thanh va su triet*.