Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach lo » sach dao, sach doi, sach hoi
lo nang » ho nang, ly nang, loai nang
mai hoi » mai khoi, dai hoi, lai hoi
hanh di » hanh vi, hanh de, hang di
ma hoi » xa hoi, ma hoa, me hoi
thu va » thuc va, thue va, thu ha
di cua » dai cua, doi cua, de cua

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 lo nang ((ma hoi) or (mai hoi)). hieu van nam ((thu va) OR (tu va)) hanh di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach lo nang ((ma hoi) OR (mai hoi)). hieu van nam ((thu va) OR (tu va)) hanh di cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach lo nang ((ma hoi) or (mai hoi)). hieu van nam ((thu va) OR (tu va)) hanh di cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach lo nang ((ma hoi) or (mai hoi)). hieu van nam ((thu va) OR (tu va)) hanh di cua vat*.