Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
thuc dan » thuc hanh, hoc dan, thuc vat
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
hanh ve » hanh va
x hoi » xa hoi, o hoi, x ho

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