Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
vat hanh » vat thanh, van hanh, va hanh
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
hoa hoi » khoa hoi, hoa doi, hoc hoi
ve nam » he nam, va nam, te nam
le nam » ly nam, he nam, le na
kem » kiem

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky dang ((hoa hoi) or (hoa hoc)). hieu ((ve nam) OR (le nam)) thuc vat hanh kem su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky dang ((hoa hoi) OR (hoa hoc)). hieu ((ve nam) OR (le nam)) thuc vat hanh kem su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky dang ((hoa hoi) or (hoa hoc)). hieu ((ve nam) OR (le nam)) thuc vat hanh kem su triet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky dang ((hoa hoi) or (hoa hoc)). hieu ((ve nam) OR (le nam)) thuc vat hanh kem su triet*.