Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
vien cac » vien bach, vien dai, vien da
thuc dan » thuc hanh, hoc dan, thuc vat
thuc day » thuc vat
sach ky » sac ky, sach y, sach ty
hanh de » hanh ve, hanh kem
so sach » so sanh, bo sach, co sach
ve cam » ve cham, ve cac, va cam
x hoi » xa hoi, o hoi, x ho
de va » de van, te va, ke 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 ky nang x hoi. hieu ((ve cam) or (vien cac)) ((thuc day) OR (thuc dan)) hanh de va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang x hoi. hieu ((ve cam) OR (vien cac)) ((thuc day) OR (thuc dan)) hanh de va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang x hoi. hieu ((ve cam) or (vien cac)) ((thuc day) OR (thuc dan)) hanh de va trien".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang x hoi. hieu ((ve cam) or (vien cac)) ((thuc day) OR (thuc dan)) hanh de va trien*.