Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
tham thuc » nham thuc, tam thuc, thai thuc
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
vu dang » su dang, vu quang, cua dang
dang ma » dang mau, dang mam, dang mat
hieu va » lieu va, hieu qua
hanh ki » hanh vi, hanh ky, hanh kien
ma hoi » mai hoi, xa hoi, ma hoa
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 hoi. hieu va ((tham thuc) OR (pham thuc)) van hanh ki su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach vu dang ma hoi. hieu va ((tham thuc) OR (pham thuc)) van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach vu dang ma hoi. hieu va ((tham thuc) OR (pham thuc)) van hanh ki su triet*.