Frühwald, M C.(1999). Vasoactive intestinal peptide (VIP) and VIP receptors: Gene expression and growth modulation in medulloblastoma and other central primitive neuroectodermal tumors of childhood. International Journal of Cancer, 81(2), 165-173. doi:10.1002/(sici)1097-0215(19990412)81:2<165::aid-ijc1>3.3.co;2-s

Frühwald, Michael C. "Vasoactive Intestinal Peptide (VIP) and VIP Receptors: Gene Expression and Growth Modulation in Medulloblastoma and Other Central Primitive Neuroectodermal Tumors of Childhood". International Journal of Cancer, 81.2 ( 1999 ): 165-173.