Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
cac truc » cac tru, cac trung, sach truc
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau
dan di » danh di, dan da, dan de
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: ((thu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cac truc) OR (cau truc)) va dan di cua 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 ((cac truc) OR (cau truc)) va dan di cua 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 ((cac truc) OR (cau truc)) va dan di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) ky nang xa hoi. hieu van ((cac truc) OR (cau truc)) va dan di cua tre*.