Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, cam thu, can thuc
nam thuc » nam thuoc, am thuc, nam thu
dan danh » van danh, han danh, ban danh
danh dai » danh dau, danh di, danh sai
so sach » bo sach, co sach, hoc sach
so sanh » do sanh
nang xa » nang x, lang xa, nang ma
cua tu » cua tuc, cua su, cua cu

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) or (so sanh)) ky nang xa hoi. hieu van ((cam thuc) OR (nam thuc)) dan danh dai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ky nang xa hoi. hieu van ((cam thuc) OR (nam thuc)) dan danh dai cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (so sanh)) ky nang xa hoi. hieu van ((cam thuc) OR (nam thuc)) dan danh dai cua tu".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) ky nang xa hoi. hieu van ((cam thuc) OR (nam thuc)) dan danh dai cua tu*.