Multiple references to the same author but without a date
You can use the same approach as for multiple sources from a single known year, adding an additional letter. For example one way of writing it would be "(Company, n.d.-a)" and "Company, n.d.-b)", where 'n.d.' is short for "no date". Adapt as needed to meet the requirements of your citation style. The hyphen is required for the APA style, for example, but might not be universal:


  Also remember that if you have two or more “in press” or “no date” references with the same authors in the same order, you should use lowercase letters—a, b, c, and so forth—after the publication date and alphabetize the references by their titles (excluding A, An, and The; see p. 182 in the Publication Manual). The only difference between these types of references and references with publication years is that “in press” and “no date” references contain a hyphen before the a, b, and so forth:
  
  American Speech-Language-Hearing Association. (n.d.-a). The knowledge . . .
  
  American Speech-Language-Hearing Association. (n.d.-b). A strategy to . . .
  
  Schafer, G., &amp; Plunkett, K. (2011a). The power . . .
  
  Schafer, G., &amp; Plunkett, K. (2011b). Task complexity . . .
  
  Schafer, G., &amp; Plunkett, K. (in press-a). The rapid learning . . .
  
  Schafer, G., &amp; Plunkett, K. (in press-b). Sometimes a child . . .