Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
va triet » va trien, ve triet, cua triet
tu sach » thu sach, su sach, te sach
tu nang » tru nang, tu nong, tu nano
sach tu » sach thu, cach tu, sach ty
thuc va » thuc vat, thuc dan, thuc day
kinh su » kinh suu, hinh su, dinh su
tuc va » truc va, tuc xa, duc va
thiet » thieu

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 tu nang x ho. hieu van cham ((tuc va) or (thuc va)) kinh su ((va triet) OR (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang x ho. hieu van cham ((tuc va) OR (thuc va)) kinh su ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nang x ho. hieu van cham ((tuc va) or (thuc va)) kinh su ((va triet) OR (va thiet))".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang x ho. hieu van cham ((tuc va) or (thuc va)) kinh su ((va triet) OR (va thiet))*.