7Search.ccmathematics mdpi ejmrmathematics mdpi ejmrhttps://www.mdpi.com/journal/mathematicsmathematics mdpi journal impact factorhttps://www.mdpi.com/journal/jmsemathematics-mdpimathematics mdpi impact factorphilosophy of physics ejmrwww.mdpi.com/journal/ijmswww.mdpi.com/journal/ijerphhttps://www.mdpi.com/journal/ijmsmdpi-ijmshttps://www.mdpi.com/journal/jcm/instructions