Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh vi » hanh vi, thanh va, thanh ve
vien cac » vien bach, vien dai, vien da
xach tay » canh tay
tru gia » tri gia, truc giac, tran gia
sach tu » sach thu, cach tu, sach ty
xang o » lang o, tang o, dang o
ve cac » va cac
o hoc » co hoc, mo hoc, so hoc
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: so ((xach tay) or (sach tu)) xang o hoc. hieu ((ve cac) OR (vien cac)) tru gia thanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((xach tay) OR (sach tu)) xang o hoc. hieu ((ve cac) OR (vien cac)) tru gia thanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((xach tay) or (sach tu)) xang o hoc. hieu ((ve cac) OR (vien cac)) tru gia thanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: so ((xach tay) or (sach tu)) xang o hoc. hieu ((ve cac) OR (vien cac)) tru gia thanh vi su triet*.