Perhaps you should try some spelling variations:
nganh khong » nganh cong, nhanh chong, nganh nong
nghien huu » nghien cuu, nguyen huu, nhiem huu
khong hoc » khung hoc, thong hoc, khong thuoc
sach hoc » cach hoc, sach hoi, mach hoc
toan hoc » toan khoa, van hoc, tin hoc
tu sach » thu sach, su sach, te sach
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
va nhan » van nhan, ca nhan, va phan
nhan va » nhan tai, nhan dan, nhan tao

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 huu ((toan hoc) OR (hoa hoc)) nganh khong hoc mai hoi va nhan va~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien huu ((toan hoc) OR (hoa hoc)) nganh khong hoc mai hoi va nhan va".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien huu ((toan hoc) OR (hoa hoc)) nganh khong hoc mai hoi va nhan va*.