Perhaps you should try some spelling variations:
hai truc » hai trac, hang truc, thai thuc
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
dai truc » dai thuc, doan truc, dai trung
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
vi cua » vai cua, di 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 ty nang xa hoi. hieu va ((hai truc) OR (dai truc)) ((ban hanh) or (van hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang xa hoi. hieu va ((hai truc) OR (dai truc)) ((ban hanh) OR (van hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang xa hoi. hieu va ((hai truc) OR (dai truc)) ((ban hanh) or (van hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang xa hoi. hieu va ((hai truc) OR (dai truc)) ((ban hanh) or (van hanh)) vi cua tre*.