Perhaps you should try some spelling variations:
khong thuoc » khang thuoc, hong phuoc, dong thuoc
phan khong » phan hong, nhan khong, pham khong
tren phan » truyen phan, trinh phan, trung phan
sach hoi » sach doi, sach moi, cach thoi
cuu dong » cuu tong, cuu long, luu dong
cuu cong » cua cong, thu cong, cac cong
thuoc va » thuc va, thuoc ma, thuong va
phan van » pham van, thanh van, luan van
tu sach » thu sach, su sach, te sach
va phan » van phan, va phat, va phap
va hoi » xa hoi, va hoc, va hoa

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 hoi dap, nghien ((cuu dong) or (cuu cong)) tren phan khong thuoc va hoi va phan van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoi dap, nghien ((cuu dong) OR (cuu cong)) tren phan khong thuoc va hoi va phan van.
• Adding a wildcard symbol may retrieve word variants: tu sach hoi dap, nghien ((cuu dong) or (cuu cong)) tren phan khong thuoc va hoi va phan van*.