Perhaps you should try some spelling variations:
sach ky » sach y, sach ty, sach kem
va hanh » van hanh, va thanh, va danh
cac tru » ca tru, cac tro, cac thu
qua cac » cua cac
nang ra » nang ma, lang ra, nang ro
nang co » nang cao, nang doc, nang noi
sac ky » cac ky, sai ky
tru va » truc va, tu va, trung va
vi cua » vai cua, di cua
cua su » qua su

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 ky) OR (sac ky)) ((nang co) or (nang ra)) hoi. hieu qua cac tru va hanh vi cua su~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) ((nang co) OR (nang ra)) hoi. hieu qua cac tru va hanh vi cua su.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sac ky)) ((nang co) or (nang ra)) hoi. hieu qua cac tru va hanh vi cua su".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sac ky)) ((nang co) or (nang ra)) hoi. hieu qua cac tru va hanh vi cua su*.