Perhaps you should try some spelling variations:
sach trinh » sach tranh, hanh trinh, sach kinh
tai nghiem » trai nghiem, thi nghiem, trac nghiem
thiet yeu » theo yeu
hoc sach » hoc sinh, hoc cac, hoc anh
toc sach » doc sach, thuoc sach, nuoc sach
sach tai » sach bai, sach tham, sach dao
nghiem d » nghiem de, nghiem do, nghiem _
d hoc » du hoc, ad hoc, de hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( hoc sach trinh ((thiet yeu) or (thiet ke)) hoc ) or ( toc sach tai nghiem d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( hoc sach trinh ((thiet yeu) OR (thiet ke)) hoc ) OR ( toc sach tai nghiem d hoc )).
• Adding a wildcard symbol may retrieve word variants: (( hoc sach trinh ((thiet yeu) or (thiet ke)) hoc ) or ( toc sach tai nghiem d hoc ))*.