Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cau tren » cu tren, dau tren, ca tren
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
va danh » va dinh, va hanh, dia danh
ve khac » vu khac, de khac, se khac
va dan » ca dan, va dao, va dau
va cau » van cau, va cac, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky ((nang xa) or (lang xa)) hoi. hieu ve khac phuc ((va danh) or (va dan)) va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky ((nang xa) OR (lang xa)) hoi. hieu ve khac phuc ((va danh) OR (va dan)) va cau tren.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky ((nang xa) or (lang xa)) hoi. hieu ve khac phuc ((va danh) or (va dan)) va cau tren*.