Phytochemical investigations on Boswellia species [Elektronische Ressource] : comparative studies on the essential oils, pyrolysates and boswellic acids of Boswellia carterii Birdw., Boswellia serrata Roxb., Boswellia frereana Birdw., Boswellia neglecta S. Moore and Boswellia rivae Engl. / by Simla Basar