Perhaps you should try some spelling variations:
hanh hanh » hanh han, xanh hanh, nhanh thanh
cam thuc » am thuc, cam thu, can thuc
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach
vu sach » vu bach, vu khach
hieu va » lieu va, hieu qua
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho

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) or (vu sach)) y nang x hoi. hieu va ((cam thuc) OR (nam thuc)) hanh hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) y nang x hoi. hieu va ((cam thuc) OR (nam thuc)) hanh hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) y nang x hoi. hieu va ((cam thuc) OR (nam thuc)) hanh hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) y nang x hoi. hieu va ((cam thuc) OR (nam thuc)) hanh hanh di cua tre*.