Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghe thu
dan thanh » dang thanh, danh thanh, ban thanh
sach hoi » sach doi, sach moi, cach thoi
cong hoc » dong hoc, cong hoa, cong coc
mai khoi » mai khoa, tai khoa, cac khoi
khoi dan » hoi dan, choi dan, khoi can
su sach » so sach, vu sach
hoi tai » hoc tai, hoi trac
dan hoa » danh hoa, dan hoat, dan khoa
hoc mai » hoc ma, hoc dai, hoc bai

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 hoi tai, ((nghien thu) or (nghien cuu)) cong hoc dan hoa hoc mai khoi dan thanh san~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach hoi tai, ((nghien thu) OR (nghien cuu)) cong hoc dan hoa hoc mai khoi dan thanh san.
• Adding a wildcard symbol may retrieve word variants: su sach hoi tai, ((nghien thu) or (nghien cuu)) cong hoc dan hoa hoc mai khoi dan thanh san*.