Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
anh kiem » anh kien, khanh kiem, nganh kiem
cau theo » cau thi, cau tao
hieu ve » hieu va, hieu van
cam luu » tam luu
luu van » cuu van, luan van, luu hanh
van anh » van thanh, tuan anh, van minh
y nang » ky nang, ly nang, v nang
ve cam » ve cham, ve cac, va cam
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang ((o hoi) OR (o hoc)). hieu ve cam luu van anh kiem ((cau tren) OR (cau theo))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang ((o hoi) OR (o hoc)). hieu ve cam luu van anh kiem ((cau tren) or (cau theo))~".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ((o hoi) OR (o hoc)). hieu ve cam luu van anh kiem ((cau tren) or (cau theo))*.