Problem and solution Verner's law in Gothic Dating the change described by Verner's law

References

1. 
   In Proto-Germanic, voiced fricatives *[β ð ɣ] were allophones of their corresponding voiced plosives *[b d ɡ] when they occurred between vowels, semivowels, and liquid consonants. The situations where Verner's law applied resulted in fricatives in these very circumstances, so fricative *[b d ɡ] can be used in this context.
   
2. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 102.
   
3. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, pp. 107-8.
   
4. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 106.
   
5. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 106-9.
   
6. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 108-9.
   
7. 
   Verner, K. 1877. Eine Ausnahme der ersten Lautverschiebung. Zeitschrift für vergleichende Sprach-forschung auf dem Gebiete der indo-germanischen Sprachen, 23.97–130.
   
8. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 110, n. 1.
   
9. 
   R.D. Fulk, A Comparative Grammar of the Early Germanic Languages, Studies in Germanic Linguistics, 3 (Amsterdam: Benjamins, 2018), doi:10.1075/sigl.3, ISBN 978 90 272 6312 4, p. 111.
   
10. 
    Vennemann 1984:21, Kortlandt 1988:5–6, Euler and Badenheuer 2009:54-55 and 61-64.
    
11. 
    Posti, Lauri (1953). "From Pre-Finnic to Late Proto-Finnic". Finnisch-Ugrische Forschungen. XXXI: 1–91 (74–82).
    
12. 
    Kallio, Petri (2000). "Posti's Superstrate Theory at the Threshold of a New Millennium". In Laakso, Johanna (ed.). Facing Finnic: Some Challenges to Historical and Contact Linguistics. Castrenianumin toimitteita. Vol. 59.