Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cam thuc » am thuc, nam thuc, can thuc
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
cam thu » nam thu, cac thu, ca thu
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
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: ((tu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cam thuc) or (cam thu)) va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky nang xa hoi. hieu van ((cam thuc) OR (cam thu)) va danh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cam thuc) or (cam thu)) va danh vi cua tre*.