Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
dinh cuu » dinh chi
tham doc » than doc, tham do, tham nuoc
van tham » van thanh, van tuan, van chat
hieu van » hieu va, thien van, lieu va
doc sach » hoc sach, nuoc sach, dac sac
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, ma hoa
doc va » duoc va, hoc va, duc va
vi cuu » vi luu, vinh cuu

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) OR (doc sach)) ky tang ma hoi. hieu van tham doc va hanh ((vi cuu) or (dinh cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky tang ma hoi. hieu van tham doc va hanh ((vi cuu) OR (dinh cuu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky tang ma hoi. hieu van tham doc va hanh ((vi cuu) or (dinh cuu)) tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky tang ma hoi. hieu van tham doc va hanh ((vi cuu) or (dinh cuu)) tre*.