Perhaps you should try some spelling variations:
doanh khoa » toan khoa
hoc doanh » hoa doanh, hoc danh, hoc dan
sach hoi » sach doi, sach moi, cach thoi
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, su sach, te sach
cuu mon » cuu mo, cuu mot, cuu cong
mon hoc » toan hoc, dong hoc
hoi cau » hoi chu, hoc cau, hoa cau
hoc xa » hoc ma
hoi ca » hoi cua, hoi cac, hoi 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 hoi dap, nghien cuu mon hoc doanh khoa hoc xa ((hoi ca) or (hoi cau)) nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoi dap, nghien cuu mon hoc doanh khoa hoc xa ((hoi ca) OR (hoi cau)) nhan dan.
• Adding a wildcard symbol may retrieve word variants: tu sach hoi dap, nghien cuu mon hoc doanh khoa hoc xa ((hoi ca) or (hoi cau)) nhan dan*.