Perhaps you should try some spelling variations:
ngang duoc » nganh duoc, nhan duoc
cau tren » cu tren, dau tren, ca tren
duoc hoi » quoc hoi, duoc hoc, duoc si
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
nam luc » nhan luc, nam thuc, nam duoc
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
va cau » van cau, va cac, va dau

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 tu) OR (sach ty)) ngang duoc hoi. hieu van ((nam luc) or (nang luc)) va hanh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sach ty)) ngang duoc hoi. hieu van ((nam luc) OR (nang luc)) va hanh va cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) OR (sach ty)) ngang duoc hoi. hieu van ((nam luc) or (nang luc)) va hanh va cau tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) OR (sach ty)) ngang duoc hoi. hieu van ((nam luc) or (nang luc)) va hanh va cau tren*.