Perhaps you should try some spelling variations:
lang khoa » hang khoa, dang khoa, long khoa
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
khoa hoi » khoan hoi, khoa hoc, khoa doi
su triet » 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
ky lang » ky nang, ky dang, ky tang
so viet » hoc viet
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 lang khoa hoi. hieu ve nam thuc vat hanh vi ((su triet) or (((su viet) OR (so viet))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang khoa hoi. hieu ve nam thuc vat hanh vi ((su triet) OR (((su viet) OR (so viet)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang khoa hoi. hieu ve nam thuc vat hanh vi ((su triet) or (((su viet) OR (so viet))))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang khoa hoi. hieu ve nam thuc vat hanh vi ((su triet) or (((su viet) OR (so viet))))*.