Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh tu » hanh tu, nhanh tu, thanh tung
thuc dan » thuc hanh, hoc dan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cuu » van cau, van chu, van cu
nang xa » nang x, lang xa, nang ma
sang ma » tang ma, nang ma, sang tao
tu cua » hu cua, vu cua
cua te » cua tu

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 ky ((nang xa) or (sang ma)) hoi. hieu van cuu ((thuc dan) OR (thuc vat)) thanh tu cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (sang ma)) hoi. hieu van cuu ((thuc dan) OR (thuc vat)) thanh tu cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (sang ma)) hoi. hieu van cuu ((thuc dan) OR (thuc vat)) thanh tu cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (sang ma)) hoi. hieu van cuu ((thuc dan) OR (thuc vat)) thanh tu cua te*.