Perhaps you should try some spelling variations:
khong thuoc » khang thuoc, hong phuoc, dong thuoc
long thuoc » luong thuoc, dong thuoc, cong thuc
hoc nganh » hoc nhanh
sach hoc » cach hoc, sach hoi, mach hoc
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
van tai » von tai, van tuan
mo hoc » mon hoc, co hoc

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