Perhaps you should try some spelling variations:
trinh doc » trinh do, trinh hoa, trinh co
toc sach » hoc sach, doc sach, thuoc sach
dieu cua » dieu tra
tinh doi » trinh do, tinh hoc, tinh son
luat tuc » luat thue
hieu cua » hieu qua, bieu cua, hieu ca
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky sang ma hoi. ((hieu cua) or (dieu cua)) luat tuc va ((tinh doi) OR (trinh doc)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky sang ma hoi. ((hieu cua) OR (dieu cua)) luat tuc va ((tinh doi) OR (trinh doc)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky sang ma hoi. ((hieu cua) or (dieu cua)) luat tuc va ((tinh doi) OR (trinh doc)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky sang ma hoi. ((hieu cua) or (dieu cua)) luat tuc va ((tinh doi) OR (trinh doc)) cuu tre*.