Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
thu sach » tu sach, thuat sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
cac cong » cua cong
khoa hoc » hoa hoc
van tuan » van quan, van ban, anh tuan
tuan van » luan van, tran van, tan van
cong so » cong san, cong hoa
so toan » so tan, so than, bao toan
qua hai » qua hoat
xa hai » xa thai, xua hai, xa hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach hoc tap, nghien cac cong so toan khoa hoc ((xa hai) or (qua hai)) van tuan van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach hoc tap, nghien cac cong so toan khoa hoc ((xa hai) OR (qua hai)) van tuan van.
• Adding a wildcard symbol may retrieve word variants: thu sach hoc tap, nghien cac cong so toan khoa hoc ((xa hai) or (qua hai)) van tuan van*.