Perhaps you should try some spelling variations:
luat danh » luat doanh, luat canh, luan danh
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
luat dan » luat dat, luat doanh, cua dan
cam thuc » am thuc, nam thuc, cam thu
hai cau » hai chau, hai chu, hai hau
su sach » so sach
nang ma » tang ma, sang ma, nang cao
ly nang » ky nang, ly hang, ly vang
vu sach » vu bach, vu khach
van cam » van nam, van lam, van cau
ma hoi » mai hoi, xa hoi, ma hoa

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) or (vu sach)) ly nang ma hoi. hieu van cam thuc ((luat danh) OR (luat dan)) hai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ly nang ma hoi. hieu van cam thuc ((luat danh) OR (luat dan)) hai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ly nang ma hoi. hieu van cam thuc ((luat danh) OR (luat dan)) hai cau tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ly nang ma hoi. hieu van cam thuc ((luat danh) OR (luat dan)) hai cau tren*.