Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh vai » thanh hai, thanh van, thanh tai
su triet » su tien, ve triet
khoa hoi » khoan hoi, khoa hoc, khoa doi
tu sach » thu sach, su sach, te sach
thu vat » thuc vat, thu va, thuat vat
su viet » so viet
sach ky » sac ky, sach y, sach ty
hieu he » hieu ve, hiem he, hieu le
hoa hoi » hoa hoc, hoa doi, hoc hoi
ky lang » ky nang, ky dang, ky tang
he nam » ha nam, nghe 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 hoi) OR (khoa hoi)). hieu he nam thu vat thanh vai ((su triet) or (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((hoa hoi) OR (khoa hoi)). hieu he nam thu vat thanh vai ((su triet) OR (su viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang ((hoa hoi) OR (khoa hoi)). hieu he nam thu vat thanh vai ((su triet) or (su viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((hoa hoi) OR (khoa hoi)). hieu he nam thu vat thanh vai ((su triet) or (su viet))*.