Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
hoc khanh » hoc nhanh, hoc thanh, hoc hanh
khanh hoa » thanh hoa, hang hoa
sach doi » sach hoi, sach moi, sach dao
cong hoc » dong hoc, cong hoa, cong coc
mai khoi » mai khoa, tai khoa, dai khoa
cac khoi » cac thoi, cac khoan, cach thoi
nhan van » nhan dan, nhan va, phan van
tu sach » thu sach, su sach, te sach
doi tac » dong tac
va nhan » van nhan, ca nhan, va phan

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach doi tac, nghien thu cong hoc khanh hoa hoc ((mai khoi) OR (cac khoi)) va nhan van~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach doi tac, nghien thu cong hoc khanh hoa hoc ((mai khoi) OR (cac khoi)) va nhan van".
• Adding a wildcard symbol may retrieve word variants: tu sach doi tac, nghien thu cong hoc khanh hoa hoc ((mai khoi) OR (cac khoi)) va nhan van*.