Perhaps you should try some spelling variations:
yen lang » den lang, ten lang, yen giang
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
qua cau » quan cau, qua cac, qua ca
van hoc » van hoa
o lang » hoa lang, hoi lang
luc va » duc va, tuc va, loc va
di cua » dai cua, doi cua, do cua
de cua » le cua, te cua, dieu cua

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 ((yen lang) or (o lang)) van hoc. hieu qua cau luc va hanh ((di cua) OR (de cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((yen lang) OR (o lang)) van hoc. hieu qua cau luc va hanh ((di cua) OR (de cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((yen lang) or (o lang)) van hoc. hieu qua cau luc va hanh ((di cua) OR (de cua)) te".
• Adding a wildcard symbol may retrieve word variants: tu sach ((yen lang) or (o lang)) van hoc. hieu qua cau luc va hanh ((di cua) OR (de cua)) te*.