Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach, vu sach
vu nang » vuc nang, va nang, vu dang
hieu ve » hieu va, hieu van
ma hoi » mai hoi, xa hoi, ma hoa
y nang » ky nang, ly nang, v nang
ve cam » ve cham, ve cac, va cam
vi su » ve su, ki su, oi su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((y nang) or (vu nang)) ma hoi. hieu ve cam thuc van hanh ((vi su) OR (va su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (vu nang)) ma hoi. hieu ve cam thuc van hanh ((vi su) OR (va su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y nang) or (vu nang)) ma hoi. hieu ve cam thuc van hanh ((vi su) OR (va su)) triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) or (vu nang)) ma hoi. hieu ve cam thuc van hanh ((vi su) OR (va su)) triet*.