Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
trien khat » trien khai, trien thuat, trien nha
khat khoa » khuan khoa, pham khoa, vat khoa
doc sach » hoc sach, toc sach, nuoc sach
sach xin » sach kinh, sach tien, sach xa
chi khoa » nhi khoa, chua khoa, thai khoa
khoa hoc » hoa hoc
xin chi » tin chi, dinh chi, linh chi
su sach » so sach, vu sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( doc sach xin chi khoa hoc ) or ( su sach trien khat khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( doc sach xin chi khoa hoc ) OR ( su sach trien khat khoa hoc )).
• Adding a wildcard symbol may retrieve word variants: (( doc sach xin chi khoa hoc ) or ( su sach trien khat khoa hoc ))*.