Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh de » hanh de, thanh ve, thanh do
thuc dan » thuc hanh, thuc vat
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
nang xa » lang xa, nang ma, mang xa
de cua » le cua, te cua, dieu 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: su sach ty ((nang xa) or (nang x)) hoi. hieu van nam ((thuc dan) OR (hoc dan)) thanh de cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (nang x)) hoi. hieu van nam ((thuc dan) OR (hoc dan)) thanh de cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang xa) or (nang x)) hoi. hieu van nam ((thuc dan) OR (hoc dan)) thanh de cua te".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang xa) or (nang x)) hoi. hieu van nam ((thuc dan) OR (hoc dan)) thanh de cua te*.