Perhaps you should try some spelling variations:
sach tien » sach tren, sach thieu
tien chai » tieng thai, tien khi, trien chi
chai khoa » thai khoa, chi khoa, pham khoa
khien chi » kien chi, khien khi, khien phi
khien cho » khien hoc, hiem cho, dien cho
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach
tu mach » tu cach, tu manh, tu hach

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 tien chai khoa hoc ) or ( tu mach ((khien chi) OR (khien cho)) khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tien chai khoa hoc ) OR ( tu mach ((khien chi) OR (khien cho)) khoa hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach tien chai khoa hoc ) or ( tu mach ((khien chi) OR (khien cho)) khoa hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach tien chai khoa hoc ) or ( tu mach ((khien chi) OR (khien cho)) khoa hoc ))*.