Perhaps you should try some spelling variations:
vien cac » vien dai, vien da, gian cac
truc gia » truc giac, tuc gia, thuc giai
thanh vi » hanh vi, thanh va, thanh ve
ve triet » va trien, su triet
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
vi ve » va ve, gi ve, ve ve

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty ((xang x) or (nang x)) hoi. hieu ((vien cac) OR (vien bach)) truc gia thanh vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((xang x) OR (nang x)) hoi. hieu ((vien cac) OR (vien bach)) truc gia thanh vi ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((xang x) or (nang x)) hoi. hieu ((vien cac) OR (vien bach)) truc gia thanh vi ve triet".
• Adding a wildcard symbol may retrieve word variants: so sach ty ((xang x) or (nang x)) hoi. hieu ((vien cac) OR (vien bach)) truc gia thanh vi ve triet*.