Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham thuc » nham thuc, tham thuc, pham thuoc
hieu van » hieu va, thien van, lieu va
vat hanh » vat thanh, van hanh, va hanh
cua viet » ca viet, hoa viet, cua vat
so sanh » do sanh
nang ma » tang ma, sang ma, nang cao
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sanh) or (cho sinh)) y nang ma hoi. hieu van ((cham thuc) OR (pham thuc)) vat hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sanh) OR (cho sinh)) y nang ma hoi. hieu van ((cham thuc) OR (pham thuc)) vat hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sanh) or (cho sinh)) y nang ma hoi. hieu van ((cham thuc) OR (pham thuc)) vat hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: ((so sanh) or (cho sinh)) y nang ma hoi. hieu van ((cham thuc) OR (pham thuc)) vat hanh vi cua viet*.