All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
We do not see anything wrong with placing a book on the ground if it is placed in a manner that does not imply disrespect and is not regarded as disrespect or mistreatment according to custom. Shaykh Ibn ‘Uthaymeen was asked about the ruling on placing the Quran on the ground on the carpet in the Masjid as some scholars held that such an act results in disbelief and removes the one who does it from the fold of Islam. He answered: “There is nothing wrong with that; this is permissible as long as it is placed in a decent manner that does not imply disrespect, as is the case when placing it in front of someone or next to him. There is no harm in that and it does not constitute an act of disbelief. However, if someone places it between his feet, may Allaah forbid, and he is a believer, undoubtedly this is regarded as disrespectful to the speech of Allaah, The Exalted…”
Shaykh Ibn Baaz was asked about placing the Quran on the ground for a long or short period of time and whether it should be placed on a high place – at least one span high - or not. He replied: “It is better to place the Quran on a high place like a chair or shelf, for example, so that it is higher than the ground. However, if it is placed on the ground for a necessity without the intention of disrespect, and the ground is pure, as is the case when the person is performing prayer, and there is no high place available to place the Quran or while he performs the prostration of recitation, for instance, then there is nothing wrong with placing it on the ground . . .”
Since it is permissible to place the Quran on the ground, then it is permissible to place other books on the ground with greater reason.
Allaah Knows best.