You should read the specific licenses to know what the conditions are. The license for this image is CC BY SA 3.0, where the full license is here. What you must do is
keep intact all copyright notices for the Work and provide, reasonable
to the medium or means You are utilizing: (i) the name of the Original
Author (or pseudonym, if applicable) if supplied, and/or if the
Original Author and/or Licensor designate another party or parties
(e.g., a sponsor institute, publishing entity, journal) for
attribution ("Attribution Parties") in Licensor's copyright notice,
terms of service or by other reasonable means, the name of such party
or parties; (ii) the title of the Work if supplied; (iii) to the
extent reasonably practicable, the URI, if any, that Licensor
specifies to be associated with the Work, unless such URI does not
refer to the copyright notice or licensing information for the Work;
and (iv) , consistent with Ssection 3(b), in the case of an
Adaptation, a credit identifying the use of the Work in the Adaptation
(e.g., "French translation of the Work by Original Author," or
"Screenplay based on original Work by Original Author"). The credit
required by this Section 4(c) may be implemented in any reasonable
manner; provided, however, that in the case of a Adaptation or
Collection, at a minimum such credit will appear, if a credit for all
contributing authors of the Adaptation or Collection appears, then as
part of these credits and in a manner at least as prominent as the
credits for the other contributing authors.
In this case, I guess they didn't read the license; or, they think that it is unreasonable to link to the original source; or, there is some behind the scenes agreement between Lamiot and Glrx. The theory in this case is that you can trace from Glrx to the photographer, via these links. "And/or" simply mean you have to do at least one of those things e.g. give the name of the Licensor, or pseudonym which is applicable here.
So yes, you must give credit. Include the information (name, title, url) in the book, either next to the picture, or in a table of credits.