Perhaps you should try some spelling variations:
sach han » sach tham, sach danh, sach nang
sach van » sach va, bach van, cach van
dao tuc » dao duc
cao tuc » cao duc, cao suc, cao toc
hieu va » lieu va, hieu qua
nang o » nang co, nang ho, nang ro
va dat » va dao, va dau, va dap
cua te » cua tu
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((sach van) or (sach han)) nang o hoi. hieu va ((cao tuc) OR (dao tuc)) va dat dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach van) OR (sach han)) nang o hoi. hieu va ((cao tuc) OR (dao tuc)) va dat dai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach van) or (sach han)) nang o hoi. hieu va ((cao tuc) OR (dao tuc)) va dat dai cua te*".