OpenStax
Open Stax: Anatomy & Physiology: Patterns of Inheritance
Students learn about patterns of inheritance including genotype and phenotype, and then learn about the inheritance of autosomal dominant and recessive and sex-linked genetic disorders.
Other
North Dakota State Univ.: Detecting and Measuring Linkage
A good site to establish what is meant by gene linkage and sex-linkage.
National Health Museum
Access Excellence: Inheritance of Hemophilia
This site explains the X-linked inheritance of Hemophilia and includes a diagram.