Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham thuc » nham thuc, tham thuc, pham thuoc
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach tu, sach thu
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa
dai va » mai va
doi va » hoi va, noi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty nang ma hoi. hieu va ((cham thuc) OR (pham thuc)) van hanh ((dai va) or (doi va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang ma hoi. hieu va ((cham thuc) OR (pham thuc)) van hanh ((dai va) OR (doi va)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang ma hoi. hieu va ((cham thuc) OR (pham thuc)) van hanh ((dai va) or (doi va)) triet*".