Perhaps you should try some spelling variations:
thien van » thi van
cau tren » cu tren, dau tren, ca tren
quang x » quang _, quang d, quang xuc
quang y » quan y, quang _, quang d
sach le » cach le, sach de, sach lo
cac duc » cac du, cao duc, cac nuoc
cac dac » cac dan, cac dai, cac bac
va hanh » van hanh, va thanh, va danh
vu sach » vu bach, su sach, vu khach
vi cau » va cau, ve cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach le ((quang x) or (quang y)) ho. thien van ((cac duc) OR (cac dac)) va hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach le ((quang x) OR (quang y)) ho. thien van ((cac duc) OR (cac dac)) va hanh vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach le ((quang x) or (quang y)) ho. thien van ((cac duc) OR (cac dac)) va hanh vi cau tren".
• Adding a wildcard symbol may retrieve word variants: vu sach le ((quang x) or (quang y)) ho. thien van ((cac duc) OR (cac dac)) va hanh vi cau tren*.