Perhaps you should try some spelling variations:
theo chieu » theo tieu, ho chieu, theo chu
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
nang cong » nang song, dang cong, bang cong
tac toan » tap toan, tam toan, hach toan
bai toan » bai tap
tinh va » tich va, trinh van, trinh vat
va nang » van nang, da nang, cam nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc hien) or (theo chieu)) xanh - hanh tinh va nang cong ((tac toan) or (bai toan)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc hien) OR (theo chieu)) xanh - hanh tinh va nang cong ((tac toan) OR (bai toan)) ban.
• Adding a wildcard symbol may retrieve word variants: ((hoc hien) or (theo chieu)) xanh - hanh tinh va nang cong ((tac toan) or (bai toan)) ban*.