Hello Everybody, 


Is there a proof of Sobolev embedding theorem without using the GNS or Morrey inequalities? If so, can you provide me with some references? 


**Background:** I happened to attened a talk on Computational PDEs and Sobolev spaces. The speaker made a reference to a proof by S. L. Sobolev using polynomials. But, unfortunately he does not remember any references. 


Thank you in advance. 



Sobolev embedding proof without Gagliardo–Nirenberg–Sobolev inequality or Morrey's inequality
There is an English translation of Sobolev's book containing his original proof:


Sobolev, S. L. Some applications of functional analysis in mathematical physics. Translated from the third Russian edition by Harold H. McFaden. With comments by V. P. Palamodov. Translations of Mathematical Monographs, 90. American Mathematical Society, Providence, RI, 1991.


