Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, cau phuc
can thuc » dan thuc, van thuc, cay thuc
dan dien » doan dien, danh dien, dan den
nang xa » nang x, lang xa, nang ma
va dan » ca dan, va dao, va dau
tu tre » tu tren, tu te, tuoi tre

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cau thuc) OR (can thuc)) va dan dien tu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ky nang xa hoi. hieu van ((cau thuc) OR (can thuc)) va dan dien tu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cau thuc) OR (can thuc)) va dan dien tu tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cau thuc) OR (can thuc)) va dan dien tu tre*.