Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
toc sach » hoc sach, doc sach, thuoc sach
tham tuc » thai tuc, nham thuc, pham thuc
dinh dau » dinh dat, dinh du, danh dau
sang ma » tang ma, sang tao, mang may
thi van » thi lan, thi hanh, thi nang
sach ky » sac ky, sach y, sach ty
va dinh » van dinh, va kinh, va tinh
nang ma » tang ma, nang cao, mang may
dau cua » dai cua, day cua, cau cua
cua tre » cua te, cuu tre, cua triet

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 ((nang ma) OR (sang ma)) hoi. thi van ((tham tuc) or (tham thuc)) va dinh dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang ma) OR (sang ma)) hoi. thi van ((tham tuc) OR (tham thuc)) va dinh dau cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((nang ma) OR (sang ma)) hoi. thi van ((tham tuc) or (tham thuc)) va dinh dau cua tre*".