Perhaps you should try some spelling variations:
mach khien » mach dien, cach thien
sach trien » sach tien, sach tren, sach thieu
trien chi » trien thi, trien khai, trieu thi
khien che » khien cho, khien he, bien che
chi khoa » nhi khoa, chua khoa, thai khoa
khoa hoc » hoa hoc
che khoa » chua khoa, chai khoa, chia khoa
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 trien chi khoa hoc ) or ( tu mach khien che khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach trien chi khoa hoc ) OR ( tu mach khien che khoa hoc ))*.