Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
thuc day » thuc dan, thuc vat
day hang » dat hang, dai hang, day nang
cao hoc » co hoc, cho hoc, chat hoc
hieu va » lieu va, hieu qua
hang di » hang doi, hang vi, hang dien
y nang » ky nang, ly nang, v nang
di cua » dai cua, doi cua, de 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: thu sach y nang ((cao hoc) or (cau hoi)). ((hieu van) OR (hieu va)) pham thuc day hang di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((cao hoc) OR (cau hoi)). ((hieu van) OR (hieu va)) pham thuc day hang di cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((cao hoc) or (cau hoi)). ((hieu van) OR (hieu va)) pham thuc day hang di cua te".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((cao hoc) or (cau hoi)). ((hieu van) OR (hieu va)) pham thuc day hang di cua te*.