Perhaps you should try some spelling variations:
tren thuoc » trien thuoc, tren thuc, trung thuoc
khoan phan » khoan phai, khoan thanh, hoa phan
thuoc sach » hoc sach, nuoc sach, thuat sach
thieu cua » hieu cua, dieu cua, bieu cua
phan cong » thanh cong
sach tren » sach tien, sach tranh
sach khoa » bach khoa, sach nha, anh khoa
pho thong » he thong
thu sach » tu sach, thuat sach, thu hoach
khoa pho » khoa phu, khoa khoa, khoa phau
vu sach » vu bach, su sach, vu khach

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 thieu cua cac khoan phan cong ) or ( thu sach tren thuoc sach khoa pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu sach thieu cua cac khoan phan cong ) OR ( thu sach tren thuoc sach khoa pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( vu sach thieu cua cac khoan phan cong ) or ( thu sach tren thuoc sach khoa pho thong ))*.