Perhaps you should try some spelling variations:
sach tien » sach tren, sach thieu
tien chao » dien cho, tien cua, tien giao
chao khoa » chai khoa, thao khoa, cao khoa
khien cho » khien hoc, hiem cho, dien cho
khoa hoc » hoa hoc
cho khoa » chi khoa, che khoa, cao khoa
tu sach » thu sach, su sach, te sach
tu mach » tu cach, tu hach, tim mach
tu manh » tu minh, tu hanh, vu manh

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