Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
duc thanh » duc thang, duc tan, de thanh
toc sach » hoc sach, doc sach, thuoc sach
sach hoi » sach doi, sach moi, cach thoi
cong duc » cong suc, hong duc, cong dac
cong hoc » dong hoc, cong hoa, cong coc
hoi tap » hoi dap, hoc tap, hoi tai
va nhan » van nhan, ca nhan, va nha
va phan » van phan, va phat, va phap
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach hoi tap, nghien thu cong duc thanh cong hoc ma hoi ((va nhan) OR (va phan)) van~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach hoi tap, nghien thu cong duc thanh cong hoc ma hoi ((va nhan) OR (va phan)) van".
• Adding a wildcard symbol may retrieve word variants: toc sach hoi tap, nghien thu cong duc thanh cong hoc ma hoi ((va nhan) OR (va phan)) van*.