Perhaps you should try some spelling variations:
nang cau » nang cao, hang cau, nang dau
hieu van » hieu va, thien van, lieu va
thuc cao » thuoc cao, thuc co, thuc can
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
thuc ca » thuc cua, thuc can, thuc va
ca cau » cua cau, cac cau, can cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang cau hoi. hieu van nam ((thuc ca) OR (thuc cao)) dan ca cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang cau hoi. hieu van nam ((thuc ca) OR (thuc cao)) dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cau hoi. hieu van nam ((thuc ca) OR (thuc cao)) dan ca cau tren*.