Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh vi » hanh vi, thanh va, thanh ve
hieu van » hieu va, thien van, lieu va
van nhan » van phan, van thanh, danh nhan
ly vang » ly hang, ly van, ly quang
duc van » duc va, duc tan, duc manh
ly nang » ky nang, ly hang, ly quang
tu sach » thu sach, su sach, te sach
luc va » duc va, tuc va, loc va
vi su » va su, ve su, ki 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 ((ly nang) OR (ly vang)) xa hoi. hieu van nhan ((luc va) or (duc van)) thanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly nang) OR (ly vang)) xa hoi. hieu van nhan ((luc va) OR (duc van)) thanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly nang) OR (ly vang)) xa hoi. hieu van nhan ((luc va) or (duc van)) thanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly nang) OR (ly vang)) xa hoi. hieu van nhan ((luc va) or (duc van)) thanh vi su triet*.