Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
phan cua » than cua, phat cua, han cua
nhan cua » nhat cua, nhan luc, nhan su
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
nam tuc » nam thuc, nam truc, nam tu
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 lang) or (ky dang)) xa hoi. hieu van nam tuc va thanh ((phan cua) OR (nhan cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky lang) OR (ky dang)) xa hoi. hieu van nam tuc va thanh ((phan cua) OR (nhan cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky lang) or (ky dang)) xa hoi. hieu van nam tuc va thanh ((phan cua) OR (nhan cua)) te".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky lang) or (ky dang)) xa hoi. hieu van nam tuc va thanh ((phan cua) OR (nhan cua)) te*.