Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
tham thuc » pham thuc, tam thuc, thai thuc
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
dang mau » dong mau, dang van, dang su
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
dang ma » dang mam, dang mat, tang ma
hieu va » lieu va, hieu qua
ki su » ky su

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 vu ((dang ma) or (dang mau)) hoi. hieu va ((tham thuc) OR (nham thuc)) van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu ((dang ma) OR (dang mau)) hoi. hieu va ((tham thuc) OR (nham thuc)) van hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach vu ((dang ma) or (dang mau)) hoi. hieu va ((tham thuc) OR (nham thuc)) van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach vu ((dang ma) or (dang mau)) hoi. hieu va ((tham thuc) OR (nham thuc)) van hanh ki su triet*.