Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
qua khoa » sua khoa, qua kho, chua khoa
cua nuoc » cua quoc, cua nguoi, cua thuoc
tan khoa » toan khoa, tran khoa, san khoa
khoa hoc » hoa hoc
van gian » van giang, dan gian, van giao
gian dan » gian lang
su sach » so sach, vu sach
doi tac » dong tac
hoc tan » hoc tang, hoc dan, hoc tap
hoi van » hoi va, hoi dan, hai van
hoc xa » hoc ma

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach doi tac, nghien ((qua khoa) or (cua nuoc)) hoc tan khoa hoc xa hoi van gian dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach doi tac, nghien ((qua khoa) OR (cua nuoc)) hoc tan khoa hoc xa hoi van gian dan.
• Adding a wildcard symbol may retrieve word variants: su sach doi tac, nghien ((qua khoa) or (cua nuoc)) hoc tan khoa hoc xa hoi van gian dan*.