Perhaps you should try some spelling variations:
nang doc » nang luc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ra » lang ra, nang ro, nang va
nang ma » tang ma, sang ma, nang cao
qua cac » cua cac
cac tru » ca tru, cac tro, cac thu
va hanh » van hanh, va thanh, va danh
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 ((nang doc) or (((nang ra) or (nang ma)))) 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 ((nang doc) OR (((nang ra) OR (nang ma)))) hoi. hieu qua cac tru va hanh vi cua su.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang doc) or (((nang ra) or (nang ma)))) hoi. hieu qua cac tru va hanh vi cua su*.