Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
thu sach » tu sach, thuat sach, thuoc sach
sang mai » sang ma, sang tai, hoang mai
lang mai » lang dai, lang hai, lang man
luc van » luoc van, luu van, duc van
sach ky » sac ky, sach y, sach ty
la tren » loai tren, dua tren, dat tren
ve cau » ke cau, va cau, ve cac
vai la » tai la, vai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((sang mai) OR (lang mai)) hoi. hieu ((ve cau) or (va cac)) luc van thanh vai la tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((sang mai) OR (lang mai)) hoi. hieu ((ve cau) OR (va cac)) luc van thanh vai la tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((sang mai) OR (lang mai)) hoi. hieu ((ve cau) or (va cac)) luc van thanh vai la tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((sang mai) OR (lang mai)) hoi. hieu ((ve cau) or (va cac)) luc van thanh vai la tren*.