Perhaps you should try some spelling variations:
thuat vat » thuat va, thuc vat, thuat xay
su triet » su viet, su tien, ve triet
hanh va » hang va, hanh vi
thu vat » thuc vat, thu va, thu nhat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hoc doi » hoc dai, hoc noi, hoc moi
hoa doi » hoa dai, xoa doi, hoa duoc
ky lang » ky nang, ky dang, ky tang
hieu ve » hieu va, hieu van
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 ((hoa doi) OR (hoc doi)). hieu ve nam ((thu vat) or (thuat vat)) hanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((hoa doi) OR (hoc doi)). hieu ve nam ((thu vat) OR (thuat vat)) hanh va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang ((hoa doi) OR (hoc doi)). hieu ve nam ((thu vat) or (thuat vat)) hanh va su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((hoa doi) OR (hoc doi)). hieu ve nam ((thu vat) or (thuat vat)) hanh va su triet*.