What is the ruling on going to the International Book Fair, which involves severe mixing, dancing, and unveiled women, knowing that the desired books may be available online or in other places?

The general rule is that it is not permissible to attend gatherings where there are objectionable acts, such as unlawful mixing of genders, immodest display by women, and their dancing, unless there is an urgent need and one is safe from temptation. In such a case, it is permitted only to the extent of fulfilling that need. Based on this, it is not permissible to go to the aforementioned exhibition as there is no need to go to it.