Perhaps you should try some spelling variations:
hoan thanh » hoang thanh, ban thanh, van thanh
sach hoc » cach hoc, sach hoi, mach hoc
dan nhan » danh nhan, dan chan, van nhan
tu sach » thu sach, su sach, te sach
mo hoan » moc hoang, hop hoan, ho khoan
hoi dan » hoa dan, hoc dan, hoi dap
nhan va » nhan tai, nhan dan, nhan tao
coc xa » hoc xa, cac xa, coc va
coc ha » hoc ha, toc ha, coc va

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 hoc tap, nghien cuu mo hoan thanh cong ((coc xa) OR (coc ha)) hoi dan nhan va~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien cuu mo hoan thanh cong ((coc xa) OR (coc ha)) hoi dan nhan va".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu mo hoan thanh cong ((coc xa) OR (coc ha)) hoi dan nhan va*.