并列题名：A Guide to the Unknown A Guide to the Unknown 并列题名：Into the unknown 并列题名：Invasion of the unknown 并列题名：Lincoln the unknown 并列题名：Field guide to the weapons 并列题名：Trail guide to the body 并列题名：User's guide to the universe 并列题名：Known and the unknown 并列题名：User's guide to the human mind