While there isn't one singular "top" paper specifically limited to Android 5.1.1, several high-impact academic studies analyze the Google Play Store ecosystem and APK security during the era of Android 5.0-6.0 (Lollipop/Marshmallow).
Corrupted cache or older Google Services Framework. Fix: google play store apk download for android 51 1 top
: An older version often cited in legacy tutorials for its "Material Design" and direct compatibility with Lollipop-era devices. How to Download and Install While there isn't one singular "top" paper specifically