Perhaps you should try some spelling variations:
nang hoa » nang hoat, hang hoa, nang ho
nang hoc » nang doc, nang luc, dong hoc
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
hanh va » hang va, hanh vi
ve nam » he nam, va nam, le nam

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 ((nang hoa) or (nang hoc)) hoi. hieu ve nam thuc vat hanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang hoa) OR (nang hoc)) hoi. hieu ve nam thuc vat hanh va su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang hoa) or (nang hoc)) hoi. hieu ve nam thuc vat hanh va su triet*.