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Echelard, Y؛ Epstein, Dj؛ St-Jacques, B؛ Shen, L؛ Mohler, J؛ Mcmahon, Ja؛ Mcmahon, Ap (ديسمبر 1993). "Sonic hedgehog, a member of a family of putative signaling molecules, is implicated in the regulation of CNS polarity". Cell. ج. 75 ع. 7: 1417–30. DOI:10.1016/0092-8674(93)90627-3. PMID:7916661.