Perhaps you should try some spelling variations:
thieu khat » thieu khang, thien phat, hieu nhat
sach tien » sach tren
chai khoa » thai khoa, chi khoa, pham khoa
khat khoa » khuan khoa, pham khoa, vat khoa
sach xin » sach kinh, sach xa, vac xin
khoa hoc » hoa hoc
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) or (sach tien)) chai khoa hoc ) or ( su sach thieu khat khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( doc ((sach xin) OR (sach tien)) chai khoa hoc ) OR ( su sach thieu khat khoa hoc )).
• Adding a wildcard symbol may retrieve word variants: (( doc ((sach xin) or (sach tien)) chai khoa hoc ) or ( su sach thieu khat khoa hoc ))*.