Perhaps you should try some spelling variations:
hoang van » hang va
nam thuc » nam thuoc, am thuc, nam thu
tinh doi » trinh doc, trinh do, tinh hoc
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, nang ma, sang tao
qua nam » quan nam, cua nam, quang nam
thuc va » thuc vat, thuc dan, thuc day
va tinh » may tinh
doi su » oi su, don su, voi su

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 ky ((sang ma) or (hoang van)) hoi. hieu qua nam thuc va tinh doi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((sang ma) OR (hoang van)) hoi. hieu qua nam thuc va tinh doi su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((sang ma) or (hoang van)) hoi. hieu qua nam thuc va tinh doi su triet*.