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License to use Roorda's work                                                                                                  < Previous page       First page >

The statement on this page sets the conditions defining when and how Niko Roorda's works can be applied.

The statement can be downloaded as a pdf file.



Roorda's productions shown on the website https://niko.roorda.nu and its subpages, that are explicitly marked as freely downloadable and applicable, including freely downloadable books, textbook accessories, computer programs, presentations, calculations, and the Pledge; as well as any texts, images, videos or anything else extracted from or produced with them, either separately or combined, are here referred to as the “free work”.

Roorda is here referred to as the "Author" of this free work.


Information and Cooperation

If you share, apply, quote or distribute the free work, the developer will be grateful if you send him a message to inform him.

If you think that the computer program and its results are material for scientific or other publications or presentations, please contact the Author with your ideas or proposals.


Computer programs: Installation

Roorda’s computer programs run in Microsoft Windows. They don’t need installation, as they are all portable. Just place the program file in a suitable location and run it.


Copyright: Creative Commons License

The free work can be distributed under the conditions of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) 3.0 license.

An explanation of this license is available at http://creativecommons.org/licenses.

The license implies that you are free:

  • to Share — to copy, distribute and transmit the free work

Under the following conditions:

  • Attribution - You must attribute the free work in the manner specified by the author (but not in any way that suggests that he endorses you or your use of the free work).
  • Noncommercial - You may not use this free work for commercial purposes, unless you have acquired explicit and written permission to do so from the Author.
  • Share Alike - If you alter, transform, or build upon this free work, you may distribute the resulting work only under the same or similar license to this one.

With the understanding that:

  • Inform — Whenever you make use of the free work, you must inform the author about this, making use of the contact data shown at https://niko.roorda.nu/contact.
  • Waiver — Any of the above conditions can be waived if you get explicit and written permission from the author.
  • Public Domain — Where the free work or any of its elements is in the public domain under applicable law, that status is in no way affected by the license.
  • Other Rights — In no way are any of the following rights affected by the license:
    • Your fair dealing or fair use rights, or other applicable copyright exceptions and limitations;
    • The author's moral rights;
    • Rights other persons may have either in the free work itself or in how the free work is used, such as publicity or privacy rights.
  • Notice — For any reuse or distribution, you must make clear to others the license terms of this free work. The best way to do this is with a link to the web page http://creativecommons.org/licenses as well as to the author's License page.

You are not free:

  • To make commercial use of the free work. If you want to do so, you need explicit and written permission from the Author.
  • To Remix — to adapt the free work.



Attributions to the free work are to be made as follows:

         [Name of the accessory / computer program / presentation / spreadsheet / etc.]
         © Niko Roorda
[If applicable: Link to webpage where the free work is to be found]


Niko Roorda, PhD

Sprang-Capelle, The Netherlands

December 2020

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