Keabsahan hukum akta jual beli yang surat kuasa jualnya dinyatakan batal demi hukum oleh hakim : analisis Putusan Pengadilan Negeri Sleman Nomor 83/Pdt.G/2013/PN.Slmn = The validity of the sale and purchase deeds that its power of attorney which is stated null and void by law : analysis of Sleman District Court decision in registration Number 83/Pdt.G/2013/PN.Slmn