Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, pham thu
nham thuc » nhan thuc, nam thuc, nham thu
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
hanh di » hanh vi, hanh de, hang di
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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