This site offers textbooks in many specific subjects such as Accounting, Business law, Business English, E-marketing, Commerce, Tourism, Hospitality management...
Open Textbook Library (OTL) provides textbooks that have been funded, published, and licensed to be freely used, adapted, and distributed. These books have been reviewed by faculty from a variety of colleges and universities to assess their quality. They can be downloaded for no cost, or printed at low cost. All textbooks are either used at multiple higher education institutions; or affiliated with an institution, scholarly society, or professional organization (Source: OTL).

Specific subjects: Communicating strategically, Digital branding and engagement, Leadership, Public speaking, Reputation management in Digital world, Tourism, Hospitality management,...
EdX is an online learning destination and MOOC provider, offering high-quality courses from the world’s best universities and institutions to learners everywhere. Currently, Edx is offering thousands of courses in various subjects for different levels of studying. (Source: edX)

JSTOR offers a growing list of Open Access ebooks from respected presses, such as University of California Press and University of Michigan Press, at no cost to libraries or users. More than 100 titles are now available, and several hundred more will be added by the end of 2017.
The ebooks, journals which reflect JSTOR’s high standards for quality content, are freely available for anyone in the world to use. Each ebook carries one of six Creative Commons licenses determined by the publisher. The titles are easy to use, with no DRM restrictions and no limits on chapter PDF downloads or printing. Users will not need to register or log in to JSTOR. (Source: JSTOR webpage)

Offering some courses in Tourism and Hospitality Management such as Tourism in Asia and the Pacific, ...

The repository provides open access to thousands of research outputs in Tourism and Hospitality Management at The University of Adelaide

Digital Scholarship@UNLV is the institutional repository of the University of Nevada, Las Vegas. It holds scholarship from UNLV faculty, staff and students. Digital Scholarship@UNLV provides a wider audience to the scholarly output of UNLV as well as assures its long-term preservation.
Many studies in Tourism and Hospitality Management are available for free access on this portal.

Florida International University (FIU) Digital Commons is a full-text, online, open access repository and publishing platform for the scholarship and creative output of FIU. It provides free resources in Tourism and Hospitality and in other topics.

The journal is published by the Faculty of Tourism and Hospitality Management, Opatija, Croatia in cooperation with T.E.I. - Alexandreion Technological Educational Institution of Thessaloniki, Department of Tourism Management, Thessaloniki, Greece and, untill 2012, with the WIFI Institut for Economic Promotion, Austrian Economic Chamber, Vienna, Austria and . The journal is supported by the Ministry of Science, Education and Sport of the Republic of Croatia. The papers can be used for personal, scientific, educational and research purposes, provided that the credit is given. The papers are licensed under CC BY-NC-SA 4.0 International license.
Tourism and hospitality management is a Sherpa/RoMEO blue journal. (Source: Portal of Scientific Journals of Croatia website)

RIT Scholar Works is the digital institutional repository for the Rochester Institute of Technology, managed by RIT Libraries at The Wallace Center. It contains the products of the research, scholarly, and creative pursuits of RIT’s faculty, staff, and students. Contents of this repository include, but are not limited to: Articles, Electronic books and book chapters, Student theses and dissertations, Open access publications (journals published by RIT Open Access Publishing), Schedules and proceedings for conferences hosted by RIT.
All of the materials in RIT Scholar Works are open access and fully accessible. (Source: RIT Scholar Works website)

ScholarWorks@UMass Amherst is a digital repository for the research and scholarly output of members of the University of Massachusetts Amherst community, administered by the UMass Amherst Libraries. It offers Hospitality & Tourism Management Masters Theses Collection from 2007 to 2013. (Source: ScholarWorks@UMass Amherst website).