Perhaps you should try some spelling variations:
thien van » thi van
cua triet » su triet, va triet
thu sach » tu sach, thuat sach, thuoc sach
dang xay » dang van, van xay
thuc dan » thuc hanh, hoc dan, thuc vat
dan hanh » dang hanh, dan khanh, dan thanh
cua viet » ca viet, hoa viet, cua vat
sach ky » sac ky, sach y, sach ty
hanh va » hang va, hanh vi
van va » van vat, van van, ban va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((nang x) or (dang xay)) hoi. thien van va thuc dan hanh va ((cua triet) OR (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang x) OR (dang xay)) hoi. thien van va thuc dan hanh va ((cua triet) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang x) or (dang xay)) hoi. thien van va thuc dan hanh va ((cua triet) OR (cua viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang x) or (dang xay)) hoi. thien van va thuc dan hanh va ((cua triet) OR (cua viet))*.