Typography 101B: The Role of White Space in Making Words Readable
http://www.stc.org/intercom/PDFs/2008/200812_29-30.pdf
  access restricted (by the publisher) to members/subscribers/customers only

Hart, Geoffrey J.S.
Intercom
2008

Abstract:

Hart continues his dissection of typography in this second installment, in which he discusses the important of spacing for the readability of words and sentences.