Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
su triet » su viet, su tien, ve triet
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
duc van » duc va, duc tan, duc manh
duc ban » duc tan, dua ban, duc man
tu sach » su sach, te sach, tu cach
van dau » van dao, phan dau
nang o » nang co, nang ho, nang ro
dat su » sat su
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) OR (thu sach)) ky nang o hoi. hieu van dau ((duc ban) or (duc van)) thanh dat su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang o hoi. hieu van dau ((duc ban) OR (duc van)) thanh dat su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky nang o hoi. hieu van dau ((duc ban) or (duc van)) thanh dat su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ky nang o hoi. hieu van dau ((duc ban) or (duc van)) thanh dat su triet*.