Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, hieu cach
trinh vatn » trinh van, trinh han, trinh san
hoc thieu » toc thieu, hoc hien
trinh vat » trinh van, trinh luat, sinh vat
nhung don » nhung van, nhung bo
dung cong » dung trong
dan khan » dan khanh, dan chan, dan than
khan cap » khan ap, than cap, khoan cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thieu sach - hanh ((trinh vat) or (trinh vatn)) ((nhung don) or (dung cong)) dan khan cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thieu sach - hanh ((trinh vat) OR (trinh vatn)) ((nhung don) OR (dung cong)) dan khan cap.
• Adding a wildcard symbol may retrieve word variants: hoc thieu sach - hanh ((trinh vat) or (trinh vatn)) ((nhung don) or (dung cong)) dan khan cap*.