Perhaps you should try some spelling variations:
thanh phan » thanh pho, thanh san, thanh toan
toan hoat » toan khoa, toan hoc, toan ho
hoat danh » hoa danh, khoan danh, hoa dan
ban thanh » ban hanh, ban hang
sach hoc » cach hoc, sach hoi, mach hoc
cuu toan » cuu hoan, cua toan, huu toan
danh hoa » thanh hoa, khanh hoa, nganh hoa
choi ban » choi dan, cho ban, chi ban
tu sach » thu sach, su sach, te sach
hoc bai » hoc giai
hoc dai » hoc dan

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 hoc tap, nghien cuu toan hoat danh hoa ((hoc bai) or (hoc dai)) choi ban thanh phan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu toan hoat danh hoa ((hoc bai) OR (hoc dai)) choi ban thanh phan.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu toan hoat danh hoa ((hoc bai) or (hoc dai)) choi ban thanh phan*.