Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh ve » hanh ve, thanh va, thanh vien
luu van » cuu van, luan van, luu hanh
sach ky » sac ky, sach y, sach ty
luc van » luoc van, duc van, luc va
hieu va » lieu va, hieu qua
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
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: toc sach ky sang ma hoi. hieu va cam ((luc van) OR (luu van)) ((thanh ve) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky sang ma hoi. hieu va cam ((luc van) OR (luu van)) ((thanh ve) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky sang ma hoi. hieu va cam ((luc van) OR (luu van)) ((thanh ve) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky sang ma hoi. hieu va cam ((luc van) OR (luu van)) ((thanh ve) or (hanh vi)) cua tre*.