Perhaps you should try some spelling variations:
sach khoa » bach khoa, sach nha, anh khoa
hoc tieng » hoc hien
tieng khi » tien khi, tieng thai, tieng noi
khoa hoc » hoa hoc
giam doc » gian doc, giam dau, gian don
tu sach » thu sach, su sach, te sach
khi cua » chi cua, thai cua
gi doc » gian doc

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 khoa hoc tieng khi cua ets : nhung ((gi doc) or (giam doc)) vi đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach khoa hoc tieng khi cua ets : nhung ((gi doc) OR (giam doc)) vi đai.
• Adding a wildcard symbol may retrieve word variants: tu sach khoa hoc tieng khi cua ets : nhung ((gi doc) or (giam doc)) vi đai*.